Exposure apparatus and device manufacturing method

ABSTRACT

An exposure apparatus illuminates a pattern with an energy beam and transfers the pattern onto a substrate via a projection optical system. The exposure apparatus includes a substrate stage on which the substrate is mounted and that moves within a two-dimensional plane holding the substrate. In addition, a supply mechanism supplies liquid to locally fill a space between the projection optical system and the substrate on the substrate stage with the liquid, and a recovery mechanism recovers the liquid. A plate is provided in at least a part of the periphery of a mounted area of the substrate on the substrate stage. The plate has a surface arranged at substantially the same height as a surface of the substrate mounted on the substrate stage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 11/147,285filed Jun. 8, 2005, which in turn is a continuation of InternationalApplication PCT/JP2003/015675, with an international filing date of Dec.8, 2003. The disclosures of these applications are hereby incorporatedherein by reference in their entireties.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to exposure apparatus and devicemanufacturing methods, and more particularly to an exposure apparatusthat is used in a lithographic process when manufacturing electronicdevices such as a semiconductor or a liquid crystal display device, anda device manufacturing method that uses such an exposure apparatus.

2. Description of the Related Art

In a lithographic process to produce electronic devices such as asemiconductor (integrated circuit) or a liquid crystal display device,projection exposure apparatus are used that transfer an image of apattern of a mask or a reticle (hereinafter generally referred to as a‘reticle’) via a projection optical system onto shot areas on a wafercoated with a resist (photosensitive agent) or a photosensitivesubstrate such as a glass plate (hereinafter referred to as a ‘glassplate’ or a ‘wafer’). Conventionally, the reduction projection exposureapparatus based on a step-and-repeat method (the so-called stepper) hasbeen widely used as such a projection exposure apparatus; however,recently, the type of projection exposure apparatus that performsexposure while the reticle and the wafer are synchronously scanned (theso-called scanning stepper) is also drawing attention.

The resolution of the projection optical system installed in theprojection exposure apparatus becomes higher when the exposurewavelength used is shorter or when the numerical aperture (NA) of theprojection optical system is higher. Therefore, in order to cope withfiner integrated circuits, the exposure wavelength used in a projectionexposure apparatus is becoming shorter year by year and the numericalaperture of the projection optical system becoming higher. Thewavelength widely used for exposure at present is 248 nm generated bythe KrF excimer laser; however, the wavelength generated by the ArFexcimer laser, 193 nm, which is shorter, has also been put to practicaluse.

In addition, when exposure is performed, depth of focus (DOF) is alsoequally important as resolution. Resolution R and depth of focus δ canbe expressed as the following equations.R=k ₁ ·λ/NAδ=k ₂ ·λ/NA ²

In this case, λ is the exposure wavelength, NA is the numerical apertureof the projection optical system, and k₁ and k₂ are processcoefficients. From equations (1) and (2), it can be seen that whenexposure wavelength k is shortened and numerical aperture NA increasedfor a higher resolution R, depth of focus δ becomes narrower. In aprojection exposure apparatus, however, because exposure is performed inan auto-focus method where the surface of the wafer is adjusted so thatit matches the image plane of the projection optical system, a widedepth of focus δ is preferable to some extent. Therefore, proposals forsubstantially widening the depth of focus have been made in the past,such as the phase shift reticle method, the modified illuminationmethod, and the multiplayer resist method.

As is described above, in the conventional projection exposureapparatus, depth of focus is becoming narrower due to shorter wavelengthof the exposure light and larger numerical aperture of the projectionoptical system. And, in order to cope with higher integration of theintegrated circuits, it is certain that the exposure wavelength willbecome much shorter in the future; however, in such a case, the depth offocus may become too narrow so that there may not be enough marginduring the exposure operations.

Accordingly, a proposal on an immersion method has been made as a methodfor substantially shortening the exposure wavelength while enlarging(widening) the depth of focus more than the depth of focus in the air.In this immersion method, resolution is improved by filling a spacebetween the lower surface of the projection optical system and thesurface of the wafer with liquid such as water or an organic solvent tomake use of the fact that the wavelength of the exposure light in theliquid becomes 1/n of the wavelength in the air (n is the refractiveindex of the liquid which is normally around 1.2 to 1.6). In addition,when this immersion method is applied, the depth of focus issubstantially enlarged n times when comparing it with the case when thesame resolution is obtained without applying the immersion method to theprojection optical system (supposing that such a projection opticalsystem can be made). That is, the depth of focus is enlarged n timesthan in the atmosphere (for example, refer to the pamphlet ofInternational Publication Number WO99/49504 or the like).

According to the projection exposure method and the apparatus disclosedin International Publication Number WO99/49504 referred to above(hereinafter referred to as ‘conventional art’), the immersion methodallows exposure to be performed with high resolution as well as agreater depth of focus than in the air, and also allows the liquid to befilled stably between the projection optical system and the substrate,that is, allows the liquid to be held, even when the projection opticalsystem and the wafer are relatively moved.

In the conventional art, however, it was difficult to recover the liquidcompletely, and it was highly probable for the liquid used for immersionto remain on the wafer. In such a case, the heat of vaporization whenthe remaining liquid vaporizes was likely to cause a temperaturedistribution or a refractive index change in the atmosphere, and suchphenomena could cause a measurement error in the laser interferometerused for measuring the position of the stage on which the wafer ismounted. Furthermore, the remaining liquid on the wafer could flow tothe back of the wafer, making the wafer stick to the carrier arm anddifficult to separate. In addition, the gas (air) flow of the atmospherearound the liquid could be distorted with the liquid-recovery operation,which could cause a temperature distribution or a refractive indexchange in the atmosphere.

In addition, in the conventional art, when exposing an edge shot on thewafer, in the case the projection area of the projection optical systemwas located near the edge of the wafer, the liquid could leak outsidethe wafer which would interfere with the favorable image forming of theprojected image of the pattern. Furthermore, when the wafer was notavailable underneath the projection optical system, it was difficult tohold the liquid referred to above; therefore, when exposure was to beginafter wafer exchange on a wafer that has been exchanged, the start hadto be delayed until the wafer was moved under the projection opticalsystem and the liquid has been supplied to a space between theprojection optical system and the wafer.

In addition, peripheral units such as a sensor like a focus sensor oran-alignment sensor have to be arranged in the vicinity of theprojection optical system. In the conventional art, however, because thesupply piping, the recovery piping, and the like were arranged on theouter side of the projection optical system, the degree of freedom waslimited when such peripheral units were disposed.

In addition, in the conventional art, bubbles could be found or formedin the supplied liquid, and when such bubbles come in the space betweenthe projection optical system and the substrate, not only did theydecrease the transmittance of the exposure light and cause unevenexposure but could also cause defective imaging when the projected imageof the pattern is formed.

Furthermore, because the exposure light irradiates the liquid betweenthe projection optical system and the substrate, a temperature change (arefractive index change) could occur in the liquid, which may degradethe imaging quality of the pattern. In addition, the pressure of theliquid between the projection optical system and the substrate may causethe wafer stage that holds the projection optical system and the waferto vibrate or to incline, which would degrade the transfer accuracy ofthe pattern onto the wafer. Moreover, when the liquid flows with respectto the projection optical system in the projection area of the pattern,temperature inclination or pressure inclination related to the directionof the flow may occur, which may be the cause of aberration of theprojection optical system such as inclination of the image plane or thecause of partial degrading in transfer accuracy of the pattern, whichdeteriorates the line width uniformity of the transferred image of thepattern.

Accordingly, various improvements can be made to the examples of theconventional art referred to above.

SUMMARY OF THE INVENTION

The present invention was made under such circumstances, and accordingto a first aspect of the present invention, there is provided a firstexposure apparatus that illuminates a pattern with an energy beam andtransfers the pattern onto a substrate via a projection optical system,the exposure apparatus comprising: a substrate stage on which thesubstrate is mounted that moves within a two-dimensional plane holdingthe substrate; a supply mechanism that supplies liquid to a spacebetween the projection optical system and the substrate on the substratestage; a recovery mechanism that recovers the liquid; and an auxiliaryrecovery mechanism that recovers the liquid which could not be recoveredby the recovery mechanism.

In this exposure apparatus, the supply mechanism supplies liquid to thespace between the projection optical system and the substrate on thesubstrate stage, and the recovery mechanism recovers the liquid. In thiscase, a predetermined amount of liquid is held (filled) between (the tipof) the projection optical system and the substrate on the substratestage. Accordingly, by performing exposure (pattern transfer on thesubstrate) in this state, the immersion method is applied, and thewavelength of the exposure light on the surface of the substrate can beshortened 1/n times (n is the refractive index of the liquid) thewavelength in the air and furthermore the depth of focus is broadenedaround n times the depth of focus in the air. In addition, when theliquid supply by the supply mechanism and the liquid recovery by therecovery mechanism are performed in parallel, the liquid between theprojection optical system and the substrate is exchanged constantly,therefore, in the case when a foreign matter adheres on the wafer, theforeign matter is removed by the liquid flow. This allows-exposure withhigh resolution and a wider depth of focus compared with when exposureis performed in the air. In addition, for example, in the case asituation where the liquid could not be completely recovered by therecovery mechanism occurs, the auxiliary recovery mechanism collects theliquid that could not be recovered. Accordingly, the liquid does notremain on the substrate, which keeps the various inconveniences referredto earlier that occur due to the remaining (residual) liquid fromoccurring. Therefore, with the exposure apparatus in the presentinvention, the pattern can be transferred on the substrate with goodprecision, and the liquid remaining on the substrate can also beprevented. With the exposure apparatus in the present invention, theliquid supply by the supply mechanism and the liquid recovery by therecovery mechanism do not necessarily have to be performed at the sametime.

In this case, the exposure apparatus can further comprise: a plateprovided in at least a part of the periphery of a mounted area of thesubstrate on the substrate stage, the plate having a surface arranged atsubstantially the same height as a surface of the substrate mounted onthe substrate stage. In such a case, even when the substrate stage movesto a position where the projection optical system is away from thesubstrate in a state where the liquid is locally held between theprojection optical system and the substrate, the liquid can be heldbetween the projection optical system and the plate, therefore, itbecomes possible to prevent the liquid from flowing out.

In the first exposure apparatus of the present invention, the auxiliaryrecovery mechanism can recover remaining liquid at the rear side of theprojection optical system in a moving direction of the substrate, or theauxiliary recovery mechanism can recover remaining liquid at the frontside of the projection optical system in a moving direction of thesubstrate.

In the first exposure apparatus of the present invention, the auxiliaryrecovery mechanism can include a suction mechanism that sucks fluid.

In this case, the exposure apparatus can further comprise: a gas supplymechanism that suppresses an environmental change in the periphery ofthe liquid caused by suction operation of the suction mechanism.

According to a second aspect of the present invention, there is provideda second exposure apparatus that illuminates a pattern with an energybeam and transfers the pattern onto a substrate via a projection opticalsystem, the exposure apparatus comprising: a substrate stage on whichthe substrate is mounted that moves within a two-dimensional planeholding the substrate; a supply mechanism that supplies liquid tolocally fill a space between the projection optical system and thesubstrate on the substrate stage with the liquid; a recovery mechanismthat recovers the liquid; and a plate provided in at least a part of theperiphery of a mounted area of the substrate on the substrate stage, theplate having a surface arranged at substantially the same height as asurface of the substrate mounted on the substrate stage.

In this exposure apparatus, the supply mechanism supplies liquid to thespace between the projection optical system and the substrate on thesubstrate stage, and the recovery mechanism recovers the liquid. Theliquid supply by the supply mechanism and the liquid recovery by therecovery mechanism do not necessarily have to be performed duringexposure, however, at least during exposure, a predetermined amount ofliquid is locally held between the projection optical system and thesubstrate on the substrate stage. Accordingly, by the immersion method,exposure is performed with high resolution and a wider depth of focuscompared with when exposure is performed in the air. And, for example,even when the substrate stage moves to a position where the projectionoptical system is away from the substrate in a state where the liquid islocally held between the projection optical system and the substrate,such as when exposing the periphery on the substrate, or when exchangingthe substrate on the substrate stage after exposure has been completed,the liquid can be held between the projection optical system and theplate, which makes it possible to prevent the liquid from flowing out.In addition, for example, because the liquid can be held between theprojection optical system and the plate while the substrate is beingexchanged, it becomes possible to start exposure operation of thesubstrate without taking any time to supply the liquid. Accordingly,with the exposure apparatus in the present invention, the pattern can betransferred with good accuracy on the substrate, and the throughput alsocan be improved, especially because the time required for liquid supplyafter wafer exchange will not be necessary.

In this case, a gap formed between the plate and the substrate can beset to 3 mm and under. In such a case, even when the immersion sectionon the image plane side of the projection system is on the border of thesubstrate and the plate, such as when the substrate stage moves to aposition where the substrate is away from the projection optical systemfrom being located under the projection optical system, the liquidbetween the substrate and the plate is kept from flowing out into thegap, due to the surface tension of the liquid.

In the second exposure apparatus in the present invention, the exposureapparatus can further comprise: an interferometer that measures aposition of the substrate stage; and an air conditioning mechanism thatperforms air conditioning in the periphery of the liquid between theprojection optical system and the substrate.

In the second exposure apparatus in the present invention, liquid supplyby the supply mechanism can begin on the plate.

According to a third aspect of the present invention, there is provideda third exposure apparatus that illuminates a pattern with an energybeam and transfers the pattern onto a substrate via a projection opticalsystem, the exposure apparatus comprising: a substrate stage on whichthe substrate is mounted that moves within a two-dimensional planeholding the substrate; an interferometer that measures a position of thesubstrate stage; a supply mechanism that supplies liquid to a spacebetween the projection optical system and the substrate on the substratestage; a recovery mechanism that recovers the liquid; and an airconditioning mechanism that performs air conditioning in the peripheryof the liquid between the projection optical system and the substrate.

In this exposure apparatus, the supply mechanism supplies liquid to thespace between the projection optical system and the substrate on thesubstrate stage, and the recovery mechanism recovers the liquid. In thiscase, the liquid supply by the supply mechanism and the liquid recoveryby the recovery mechanism do not necessarily have to be performed duringexposure, however, a predetermined amount of liquid is held locallybetween the projection optical system and the substrate on the substratestage at least during exposure. Accordingly, by the immersion method,exposure is performed with high resolution and a wider depth of focuscompared with when exposure is performed in the air. In addition,because the air conditioning mechanism performs air conditioning in theperiphery of the liquid, turbulence of the gas flow can be prevented inthe atmosphere in the periphery of the liquid when recovering the liquidby the recovery mechanism, which can prevent measurement errors of theinterferometers that may occur due to the turbulence of the gas flow(including temperature fluctuation of the gas, refractive index change,and the like), and allows the position of wafer stage WST to be measuredwith good accuracy. Therefore, with the exposure apparatus in thepresent invention, the pattern can be transferred with good accuracy onthe substrate.

In this case, the air conditioning mechanism can include a suctionmechanism that sucks fluid.

In this case, the suction mechanism can also perform the function ofrecovering the liquid which could not be recovered by the recoverymechanism. In such a case, for example, when a situation where theliquid could not be completely recovered by the recovery mechanismoccurs, the suction mechanism collects the liquid that could not berecovered. Accordingly, the liquid does not remain on the substrate,which keeps the various inconveniences referred to earlier that occurdue to the remaining (residual) liquid from occurring.

In the third exposure apparatus in the present invention, the airconditioning mechanism can locally air-condition the periphery of theliquid, independent from the air-conditioning inside the chamber wherethe exposure apparatus is housed.

In each of the first to third exposure apparatus in the presentinvention, the projection optical system can include a plurality ofoptical elements in which an optical element located closest to thesubstrate has a hole formed in a section excluding a portion used forexposure, and at least one operation of supplying the liquid, recoveringthe liquid, and recovering bubbles (bubbles in the liquid) is performedvia the hole.

According to a fourth aspect of the present invention, there is provideda fourth exposure apparatus that illuminates a pattern with an energybeam and transfers the pattern onto a substrate via a projection opticalsystem, the exposure apparatus comprising: a substrate stage on whichthe substrate is mounted that moves within a two-dimensional planeholding the substrate; a supply mechanism that supplies liquid to aspace between the projection optical system and the substrate on thesubstrate stage; and a recovery mechanism that recovers the liquid,wherein the projection optical system includes a plurality of opticalelements in which an optical element located closest to the substratehas a hole formed in a section excluding a portion used for exposure,and at least one operation of supplying the liquid, recovering theliquid, and recovering bubbles is performed via the hole.

In this exposure apparatus, in the optical element that structures theprojection optical system located closest to the substrate side, a holeis formed in a section that is not used for exposure, and through thehole an operation of supplying the liquid, recovering the liquid, orrecovering bubbles in the liquid is performed. Therefore, space savingis possible compared with the case when the supply mechanism and therecovery mechanism are disposed exterior to the projection opticalsystem. In addition, also in this case, the supply mechanism suppliesliquid to the space between the projection optical system and thesubstrate on the substrate stage, and the recovery mechanism recoversthe liquid. In this case, the liquid supply by the supply mechanism andthe liquid recovery by the recovery mechanism do not necessarily have tobe performed during exposure, however, a predetermined amount of liquidis held between the projection optical system and the substrate on thesubstrate stage at least during exposure. Accordingly, by the immersionmethod, exposure is performed with high resolution and a wider depth offocus compared with when exposure is performed in the air. Therefore,with the exposure apparatus in the present invention, the pattern can betransferred with good accuracy on the substrate, and the degree offreedom of each section arranged in the periphery of the projectionoptical system also increases.

In each of the first to fourth exposure apparatus in the presentinvention, the exposure apparatus can further comprise: a control unitthat stops both liquid supply operation by the supply mechanism andliquid recovery operation by the recovery mechanism when the substratestage remains stationary.

According to a fifth aspect of the present invention, there is provideda fifth exposure apparatus that illuminates a pattern with an energybeam and transfers the pattern onto a substrate via a projection opticalsystem, the exposure apparatus comprising: a substrate stage on whichthe substrate is mounted that moves within a two-dimensional planeholding the substrate; a supply mechanism that supplies liquid to aapace between the projection optical system and the substrate on thesubstrate stage; and a recovery mechanism that recovers the liquid,wherein when the substrate stage remains stationary, both liquid supplyoperation by the supply mechanism and liquid recovery operation by therecovery mechanism are stopped.

In this exposure apparatus, when the substrate stage is stationary, boththe liquid supply operation by the supply mechanism and the liquidrecovery operation by the recovery mechanism are stopped. In this case,for example, when a projection optical system with a high resolution (aprojection optical system that has a large numerical aperture) whosedistance between the projection optical system and the substrate(working distance) is small is used, the liquid is held between theprojection optical system and the substrate by its surface tension.Because the necessity to exchange the liquid is low in most cases whilethe substrate stage is stationary, the amount of liquid used can bereduced when compared with the case when both liquid supply operation bythe supply mechanism and liquid recovery operation by the recoverymechanism are performed in parallel at all times (not only when thesubstrate stage is moving, but also when the substrate stage isstationary). In this case as well, a predetermined amount of liquid isheld between the projection optical system and the substrate on thesubstrate stage at least during exposure. Accordingly, by the immersionmethod, exposure is performed with high resolution and a wider depth offocus compared with when exposure is performed in the air. Therefore,with the exposure apparatus in the present invention, the pattern can betransferred with good accuracy on the substrate, and the amount ofliquid used can be reduced. This is especially suitable in the case whenthe liquid used is costly.

In each of the first to fifth exposure apparatus in the presentinvention, the supply mechanism can supply liquid to the space betweenthe projection optical system and the substrate on the substrate stagefrom the front side in a moving direction of the substrate, or thesupply mechanism can supply liquid to the space between the projectionoptical system and the substrate on the substrate stage from the rearside in a moving direction of the substrate.

In each of the first to fifth exposure apparatus in the presentinvention, the exposure apparatus can further comprise: a drive systemthat drives the substrate stage in a predetermined scanning directionwith respect to the energy beam to transfer the pattern onto thesubstrate in a scanning exposure method.

In this case, the supply mechanism can have a plurality of supply portsarranged spaced apart in a non-scanning direction perpendicular to thescanning direction, and the supply mechanism can supply the liquid fromat least one supply port selected from the plurality of supply ports inaccordance with the size of a divided area subject to exposure on thesubstrate.

According to a sixth aspect of the present invention, there is provideda sixth exposure apparatus that illuminates a pattern with an energybeam and transfers the pattern onto a plurality of divided areas on asubstrate respectively, via a projection optical system, the exposureapparatus comprising: a substrate stage on which the substrate ismounted that moves within a two-dimensional plane holding the substrate;a peripheral wall that surrounds at least an optical element arrangedclosest to the substrate constituting the projection optical system, andalso forms a predetermined clearance with respect to a surface of thesubstrate on the substrate stage; and at least one supply mechanism thatsupplies liquid inside the peripheral wall from the rear side in amoving direction of the substrate.

In this exposure apparatus, when the substrate is moving, that is,during the movement of the substrate stage holding the substrate, thesupply mechanism supplies the liquid inside the peripheral wall, whichincludes the space between the projection optical system and thesubstrate on the substrate stage, from the rear side in the movingdirection of the substrate, and the liquid is filled in the spacebetween the projection optical system and the substrate when thesubstrate is moved. In this case, when the predetermined divided area onthe substrate moves under the projection optical system, the liquid issupplied to the upper side of the divided area without fail before itreaches the space below the projection optical system. That is, when thesubstrate is moved in the predetermined direction, the space between theprojection optical system and the surface of the substrate is filledwith the liquid. Accordingly, by performing exposure (pattern transferon the substrate) for the divided area serving as the area subject toexposure, the immersion method is applied and exposure is performed withhigh resolution and a wider depth of focus compared with when exposureis performed in the air. And, in this way, the pattern can betransferred onto each of the plurality of divided areas on the substratewith good precision.

In this case, the exposure apparatus can further comprise: a recoverymechanism that recovers the liquid at the front side of the projectionoptical system in a moving direction of the substrate. In such a case,the supply mechanism supplies the liquid inside the peripheral wall fromthe rear side in the moving direction of the substrate, and the recoverymechanism collects the liquid at the front side of the projectionoptical system in the moving direction of the substrate. In this case,the liquid supplied flows between the projection optical system and thesubstrate along the moving direction of the substrate. Therefore, in thecase foreign matters adhere on the substrate, they are removed by theflow of the liquid.

In the sixth exposure apparatus in the present invention, the supplymechanism can have a plurality of supply ports in the periphery of anirradiation area on the substrate where the energy beam is irradiatedvia the pattern and the projection optical system on exposure, and canswitch the supply port used for supplying the liquid in accordance withthe moving direction of the substrate.

In the sixth exposure apparatus in the present invention, the exposureapparatus can further comprise: a drive system that drives the substratestage in a predetermined scanning direction with respect to the energybeam to transfer the pattern onto the substrate in a scanning exposuremethod.

In this case, the supply mechanism can be provided on one side and theother side of the irradiation area in the scanning direction,respectively, and the supply mechanism that supplies the-liquid can beswitched in accordance with the scanning direction of the substrate.

In the sixth exposure apparatus in the present invention, the supplymechanism can have a plurality of supply ports arranged spaced apart ina non-scanning direction perpendicular to the scanning direction, andthe supply mechanism can supply the liquid from at least one supply portselected from the plurality of supply ports in accordance with the sizeof a divided area subject to exposure on the substrate.

In the sixth exposure apparatus in the present invention, the exposureapparatus can further comprise: a plate provided in at least a part ofthe periphery of a mounted area of the substrate on the substrate stage,the plate having a surface arranged at substantially the same height asa surface of the substrate mounted on the substrate stage.

In each of the first to sixth exposure apparatus in the presentinvention, the exposure apparatus can further comprise: at least onebubble recovery mechanism that recovers bubbles in the liquid at therear side of the projection optical system in a moving direction of thesubstrate.

In each of the first to sixth exposure apparatus in the presentinvention, the exposure apparatus can further comprise: an adjustmentunit that adjusts exposure conditions based on at least one of actualmeasurement values and prediction values of temperature information onthe liquid between said projection optical system and said substrate.

According to a seventh aspect of the present invention, there isprovided a seventh exposure apparatus that illuminates a pattern with anenergy beam, moves a substrate in a predetermined scanning direction,and transfers the pattern onto a plurality of divided areas on thesubstrate via a projection optical system in a scanning exposure method,the exposure apparatus comprising: a substrate stage on which thesubstrate is mounted that moves within a two-dimensional plane holdingthe substrate; a supply mechanism that supplies liquid to a spacebetween the projection optical system and the substrate on the substratestage; and a recovery mechanism that recovers the liquid, wherein liquidsupply by the supply mechanism and liquid recovery by the recoverymechanism are performed in sync with exposure operations for each of thedivided areas on the substrate.

In this exposure apparatus, because liquid supply by the supplymechanism and liquid recovery by the recovery mechanism are performed insync with exposure operations for each of the divided areas on thesubstrate, when the pattern is transferred onto the divided area subjectto exposure on the substrate in a scanning exposure method, apredetermined amount of liquid (exchanged constantly) can be filled inthe space between the projection optical system and the substrate whilethe divided area passes through the irradiation area of the energy beamvia the projection optical system, and by the immersion method, exposureis performed with high resolution and a wider depth of focus comparedwith when exposure is performed in the air. Meanwhile, a state can bemade where there is no liquid on the substrate during a period otherthan the irradiation period when the divided area subject to exposurepasses through the irradiation area of the energy beam, or other than aperiod including the irradiation period and a slight length of timeafter the irradiation period. That is, on sequentially exposing theplurality of divided areas on the substrate, each time a divided area isexposed, liquid supply to the space between the projection opticalsystem and the substrate and full liquid recovery are repeatedlyperformed, which can shorten the period in which the liquid exists onthe substrate, which can also suppress degrading of substances in thephotosensitive agent (resist) on the substrate as well as suppress theenvironmental degradation of the atmosphere in the periphery of thesubstrate. In addition, the liquid heated by the irradiation of exposurelight during exposure of the preceding divided area does not affect theexposure of the following divided area.

In this case, each time exposure of each of the divided areas isperformed, the liquid supply by the supply mechanism and full recoveryof the liquid by the recovery mechanism can be performed.

In this case, on transferring the pattern, due to the substrate stagemoving in the scanning direction, the liquid supply by the supplymechanism can begin at some point before the front edge of a dividedarea subject to exposure enters an irradiation area on the substrate onwhich the energy beam is irradiated via the pattern and the projectionoptical system on exposure.

In this case, the liquid supply by the supply mechanism can begin aftermoving operation of the substrate stage between divided areas, which isperformed between pattern transfer on the divided area subject toexposure and pattern transfer on a preceding divided area, has beencompleted, or, as in the exposure apparatus of Claim 36, the liquidsupply by the supply mechanism can begin when the front edge of thedivided area subject to exposure reaches a supply position.

In the seventh exposure apparatus in the present invention, ontransferring the pattern, due to the substrate stage moving in thescanning direction, the liquid supply by the supply mechanism can stopat a point when the rear edge of a divided area subject to exposurecomes off an irradiation area on the substrate on which the energy beamis irradiated via the pattern and the projection optical system onexposure.

In this case, the liquid recovery by the recovery mechanism can endafter the pattern is transferred onto the divided area subject toexposure and before moving operation of the substrate stage betweendivided areas performed prior to pattern transfer on a succeedingdivided area begins.

In the seventh exposure apparatus in the present invention, ontransferring the pattern, due to the substrate stage moving in thescanning direction, the liquid supply by the supply mechanism can stopat a point before the rear edge of a divided area subject to exposurecomes completely off an irradiation area on the substrate on which theenergy beam is irradiated via the pattern and the projection opticalsystem on exposure.

In this case, the liquid supply by the supply mechanism can stop whenthe rear edge of the divided area subject to exposure reaches a supplyposition. In addition, the liquid recovery by the recovery mechanism canend after the pattern is transferred onto the divided area subject toexposure and before moving operation of the substrate stage betweendivided areas performed prior to pattern transfer on a succeedingdivided area begins.

In each of the fifth and seventh exposure apparatus in the presentinvention, the exposure apparatus can further comprise: a peripheralwall that surrounds at least an optical element closest to the substrateconstituting the projection optical system, and also forms apredetermined clearance with respect to a surface of the substrate onthe substrate stage, wherein the supply mechanism supplies the liquidinside the peripheral wall where an end section of the projectionoptical system on the side of the substrate fronts.

According to an eighth aspect of the present invention, there isprovided an eighth exposure apparatus that illuminates a pattern with anenergy beam, moves a substrate in a predetermined scanning direction,and transfers the pattern onto a plurality of divided areas on thesubstrate via a projection optical system in a scanning exposure method,the exposure apparatus comprising: a substrate stage on which thesubstrate is mounted that moves within a two-dimensional plane holdingthe substrate; a peripheral wall that surrounds at least an opticalelement arranged closest to the substrate constituting the projectionoptical system, and also forms a predetermined clearance with respect toa surface of the substrate on the substrate stage; a supply mechanismthat supplies liquid inside the peripheral wall; and a recoverymechanism that recovers the liquid.

In this exposure apparatus, the supply mechanism supplies the liquidinside the peripheral wall, which includes the space between theprojection optical system and the substrate on the substrate stage, andthe recovery mechanism collects the liquid. Accordingly, when the liquidsupply by the supply mechanism and the liquid recovery by the recoverymechanism are performed in parallel, a predetermined amount of liquid(exchanged at all times) is held inside the peripheral wall includingthe space between the projection optical system and the substrate.Therefore, when exposure (pattern transfer on the substrate) isperformed for the divided areas on the substrate serving as the areassubject to exposure, by performing the liquid supply and recoverydescribed above in parallel, the immersion method previously describedis applied, and exposure with high resolution and a wider depth of focuscompared with when exposure is performed in the air is performed. Inaddition, in this case, because the exposure apparatus comprises aperipheral wall that surrounds at least an optical element arrangedclosest to the substrate constituting the projection optical system andalso forms a predetermined clearance with respect to a surface of thesubstrate on the substrate stage, by setting the clearance small, thecontact area of the liquid and the outer air is set extremely small, andthe surface tension of the liquid prevents the liquid from leakingoutside the peripheral wall via the clearance. Therefore, for example,it becomes possible to recover the liquid used for immersion withoutfail after the completion of exposure. Accordingly, with the exposureapparatus in the present invention, the pattern can be transferred ontoeach of the plurality of divided areas on the substrate with goodprecision, and various adverse effects caused by the liquid remaining onthe substrate can be avoided.

In this case, the inside of the peripheral wall can be in a negativepressure state. In such a case, leakage of the liquid outside theperipheral wall due to its own weight can be prevented with morecertainty.

In the eighth exposure apparatus in the present invention, when thesubstrate stage holding the substrate is moving, the liquid supply bythe supply mechanism and the liquid recovery by the recovery mechanismcan be performed.

In the eighth exposure apparatus in the present invention, when thesubstrate stage holding the substrate is stationary, liquid supplyoperation by the supply mechanism and liquid recovery operation by therecovery mechanism can be suspended, and a state where the liquid isheld within the peripheral wall can be maintained.

In the eighth exposure apparatus in the present invention, thepredetermined clearance can be set to 3 mm and under.

According to a ninth aspect of the present invention, there is provideda ninth exposure apparatus that illuminates a pattern with an energybeam, moves a substrate in a predetermined scanning direction, andtransfers the pattern onto a plurality of divided areas on the substratevia a projection optical system in a scanning exposure method, theexposure apparatus comprising: a substrate stage on which the substrateis mounted that moves within a two-dimensional plane holding thesubstrate; and the supply mechanism that has a plurality of supply portsarranged spaced apart in a non-scanning direction perpendicular to thescanning direction, and the supply mechanism supplies the liquid alongthe scanning direction from at least one supply port selected from theplurality of supply ports in accordance with the position of a dividedarea subject to exposure on the substrate to a predetermined spatialarea, which includes at least a space between the substrate on thesubstrate stage and the projection optical system.

For example, in the case at least the size of the divided area subjectto exposure in the non-scanning direction differs depending on theposition of the divided area subject to exposure on the substrate, thesupply mechanism selecting the supply port according to the position ofthe divided area subject to exposure on the substrate consequently isequivalent to selecting the supply port according to the size of thedivided area subject to exposure in the non-scanning direction.Accordingly, with the present invention, it becomes possible to selectthe supply port corresponding the range of the divided area subject toexposure in the non-scanning direction, and by performing scanningexposure using the immersion method while supplying the liquid to thespace between the divided area subject to exposure on the substrate andthe projection optical system along in the scanning direction withoutspilling the liquid on areas other than the divided area, the patterncan be transferred onto the divided area subject to exposure with goodaccuracy. In this case, the size of a part of the divided areas on thesubstrate in the non-scanning direction may be different from that ofthe remaining divided areas, or in the case chipped divided areas arefound in the periphery of the substrate, the size of all the remainingdivided areas in the non-scanning direction may be the same.

In this case, when the divided area subject to exposure is a dividedarea in the periphery on the substrate, the supply mechanism can supplythe liquid only from a part of the plurality of supply ports spacedapart in the non-scanning direction.

According to a tenth aspect of the present invention, there is provideda tenth exposure apparatus that illuminates a pattern with an energybeam, moves a substrate in a predetermined scanning direction, andtransfers the pattern onto a plurality of divided areas on the substratevia a projection optical system in a scanning exposure method, theexposure apparatus comprising: a substrate stage on which the substrateis mounted that moves within a two-dimensional plane holding thesubstrate; and a supply mechanism that has a plurality of supply portsarranged spaced apart in a non-scanning direction perpendicular to thescanning direction, the supply mechanism supplying the liquid along thescanning direction to a predetermined spatial area, which includes atleast a space between the substrate on the substrate stage and theprojection optical system, from at least one supply port selected fromthe plurality of supply ports in accordance with the size of a dividedarea subject to exposure on the substrate in the non-scanning direction.

In this exposure apparatus, according to the size of the divided areasubject to exposure in the non-scanning direction, the supply mechanismis able to select the supply port corresponding the range of the dividedarea subject to exposure in the non-scanning direction, and byperforming scanning exposure using the immersion method while supplyingthe liquid to the space between the divided area subject to exposure onthe substrate and the projection optical system along the scanningdirection without spilling the liquid on areas other than the dividedarea, the pattern can be transferred onto the divided area subject toexposure with good accuracy. In this case, the size of a part of thedivided areas on the substrate in the non-scanning direction may bedifferent from that of the remaining divided areas, or the size of alldivided areas in the non-scanning direction may be the same. Inaddition, when scanning exposure is performed on the divided areas inthe periphery of the substrate, the size in the non-scanning directionmay gradually change, however, even in such a case, the supply port canbe selected according to the size change.

In each of the ninth and tenth exposure apparatus in the presentinvention, the exposure apparatus can further comprise: at least onebubble recovery mechanism that recovers bubbles in the liquid in theupstream side of the liquid flowing along the scanning direction withrespect to the projection optical system.

In each of the ninth and tenth exposure apparatus in the presentinvention, the supply mechanism can supply liquid from the rear side ina moving direction of the substrate.

According to an eleventh aspect of the present invention, there isprovided an eleventh exposure apparatus that illuminates a pattern withan energy beam and transfers the pattern onto a substrate via aprojection optical system, the exposure apparatus comprising: asubstrate stage on which the substrate is mounted that moves within atwo-dimensional plane holding the substrate; a supply mechanism thatsupplies liquid to a space between the projection optical system and thesubstrate on the substrate stage; and at least one bubble recoverymechanism that recovers bubbles in the liquid in the upstream side ofthe liquid flow with respect to the projection optical system.

In this exposure apparatus, when exposure (pattern transfer on thesubstrate) is performed in a state where there is liquid in apredetermined spatial area that includes the space between theprojection optical system and the substrate on the substrate stage, theimmersion method is applied and exposure with high resolution and awider depth of focus compared with when exposure is performed in the airis performed. The bubbles found in the liquid are recovered by thebubble recovery mechanism in the upstream side of the liquid flow withrespect to the projection optical system. That is, the bubbles in theliquid are recovered by the bubble recovery mechanism before they reachthe optical path of the energy beam between the projection opticalsystem and the substrate. This can prevent the transmittance of theenergy beam (exposure light) from partly decreasing, deterioration ofthe projected image, or the like, which are caused by the bubblesentering the space between the projection optical system and thesubstrate.

In this case, the bubble recovery mechanism can exhaust bubbles alongwith the liquid (which has been recovered).

In the eleventh exposure apparatus in the present invention, the bubblerecovery mechanism can be provided in plurals, and the bubble recoverymechanism used for recovering bubbles is switched in accordance with amoving direction of the substrate. In such a case, the bubbles can bekept from entering the space between the projection optical system andthe substrate while the substrate is moving, whichever direction thesubstrate moves.

In each of the ninth to eleventh exposure apparatus in the presentinvention, the exposure apparatus can further comprise: an adjustmentunit that adjusts exposure conditions based on at least one of actualmeasurement values and prediction values of temperature information onthe liquid between the projection optical system and the substrate.

According to a twelfth aspect of the present invention, there isprovided a twelfth exposure apparatus that illuminates a pattern with anenergy beam and transfers the pattern onto a substrate via a projectionoptical system, the exposure apparatus comprising: a substrate stage onwhich the substrate is mounted that moves within a two-dimensional planeholding the substrate; a supply mechanism that supplies liquid to apredetermined spatial area which includes a space between the projectionoptical system and the substrate on the substrate stage; and anadjustment unit that adjusts exposure conditions based on temperatureinformation on the liquid between the projection optical system and thesubstrate.

In this exposure apparatus, the supply mechanism supplies the liquid tothe predetermined spatial area that includes at least the space betweenthe projection optical system and the substrate on the substrate stage.When exposure (pattern transfer on the substrate) is performed in thisstate, the immersion method is applied and exposure with high resolutionand a wider depth of focus compared with when exposure is performed inthe air is performed. In this case, the adjustment unit adjusts exposureconditions based on at least one of the actual measurement values andthe prediction values of temperature information on the liquid betweenthe projection optical system and the substrate. Therefore, this allowsan appropriate adjustment of exposure conditions, taking into accountdegrading factors of the exposure accuracy that goes with thetemperature distribution of the liquid used for immersion, such as theaberration (for example, focus) distribution within the projection area(the area on the substrate where the energy beam via the pattern and theprojection optical system is irradiated) of the pattern, or in otherwords, the change in the image plane shape. Accordingly, with theexposure apparatus in the present invention, it becomes possible totransfer the pattern onto the substrate with good precision.

In this case, the exposure apparatus can further comprise: a drivesystem that drives the substrate stage in a predetermined scanningdirection with respect to the energy beam to transfer the pattern ontothe substrate in a scanning exposure method; and at least twotemperature sensors, at least each one of which is arranged on one sideand the other side of the projection optical system in the scanningdirection.

In this case, the exposure apparatus can further comprise: a predictionunit that predicts temperature change of the liquid occurring while theliquid passes through an area on the substrate where the energy beam isirradiated via the pattern and the projection optical system, based ondetection results of at least two temperature sensors arranged on oneside and the other side respectively.

In the twelfth exposure apparatus in the present invention, the exposureapparatus can further comprise: a drive system that drives the substratestage in a predetermined scanning direction with respect to the energybeam to transfer the pattern onto the substrate in a scanning exposuremethod, wherein the adjustment unit adjusts exposure conditions takinginto consideration temperature distribution of the liquid between theprojection optical system and the substrate in the scanning direction.

In this case, the adjustment unit can adjust a positional relationshipbetween an image plane and a surface of the substrate taking intoconsideration inclination of the image plane caused by the temperaturedistribution in the scanning direction.

In this case, the adjustment unit can incline the substrate according tothe inclination of the image plane caused by the temperaturedistribution in the scanning direction and can also scan the substratein a direction of the inclination.

In each of the eleventh and twelfth exposure apparatus in the presentinvention, the supply mechanism can make a flow of the liquid along amoving direction of the substrate.

In this case, the supply mechanism can make a flow of the liquid fromthe rear side in a moving direction of the substrate.

In the twelfth exposure apparatus in the present invention, thetemperature information can include at least one of actual measurementvalues and prediction values.

In the twelfth exposure apparatus in the present invention, the exposureapparatus can further comprise: a temperature sensor that can detect thetemperature of the liquid between the projection optical system and thesubstrate, wherein the exposure conditions are adjusted based ondetection results of the temperature sensor.

In the twelfth exposure apparatus in the present invention, focuscontrol in which a positional relationship between an image plane formedby the projection optical system and a surface of the substrate can beadjusted, based on the temperature information.

According to a thirteenth aspect of the present invention, there isprovided a thirteenth exposure apparatus that transfers a predeterminedpattern on a substrate via a projection optical system in a state whereliquid is filled in between the projection optical system and thesubstrate, wherein in the case multiple exposure is performed, a firstpattern is transferred onto a divided area on the substrate, and then asecond pattern is also transferred on the divided area on the substratewhile the liquid is being held between the projection optical system andthe substrate.

In this exposure apparatus, when multiple exposure is performed, afterthe first pattern is transferred onto the divided area on the substratein a state where the liquid is filled in a space between the projectionoptical system and the substrate, the second pattern is transferred ontothe divided area on the substrate with the liquid being held between theprojection optical system and the substrate. Therefore, multipleexposure to which the immersion method is applied is performed, andexposure with high resolution and high accuracy due to a substantiallywider depth of focus is performed. In this case, because the liquid isheld between the projection optical system and the substrate at thepoint when the transfer of the second pattern begins, the transferoperation of the second pattern can start without waiting for the liquidto be supplied.

According to a fourteenth aspect of the present invention, there isprovided a fourteenth exposure apparatus that exposes a substrate byprojecting an image of a pattern on the substrate via a projectionoptical system, the exposure apparatus comprising: a substrate stage onwhich the substrate is mounted that moves within a two-dimensional planeholding the substrate; a supply mechanism that supplies liquid to apredetermined spatial area which includes a space between the projectionoptical system and the substrate on the substrate stage; and anadjustment unit that adjusts exposure conditions based on pressureinformation on the liquid between the projection optical system and thesubstrate.

In this exposure apparatus, the supply mechanism supplies the liquid tothe space between the substrate on the substrate stage and theprojection optical system. When exposure (pattern transfer on thesubstrate) of the substrate is performed in this state, the immersionmethod is applied, and exposure with high resolution and a wider depthof focus compared with when exposure is performed in the air isperformed. In this case, the adjustment unit adjusts exposure conditionsbased on pressure information on the liquid between the projectionoptical system and the substrate. Therefore, this allows an appropriateadjustment of exposure conditions, taking into account degrading factorsof the exposure accuracy that goes with the pressure distributionbetween the projection optical system and the substrate due to theliquid flow, such as the change in the aberration (for example, focus)within the projection area (the area on the substrate where the energybeam via the pattern and the projection optical system is irradiated) ofthe pattern, the change in the image plane shape, or the control errorof the surface position of the substrate surface. The pressuredistribution between the projection optical system and the substrate maybe actual measurement values, which are directly measured using apressure sensor or the like, or prediction values based on informationobtained in advance by experiment or the like. In either case, thepattern can be transferred onto the substrate with good precision.

In this case, the substrate can be exposed while being moved in apredetermined scanning direction, the liquid supplied to the spacebetween the projection optical system and the substrate can flow inparallel with the scanning direction, and the adjustment unit can adjustthe exposure conditions based on pressure distribution in the scanningdirection.

In the fourteenth exposure apparatus in the present invention, thesubstrate can be exposed while being moved in the same direction as aflow direction of the liquid.

In the fourteenth exposure apparatus in the present invention, theadjustment unit can adjust the exposure conditions based on adjustmentinformation on exposure conditions corresponding to a scanning speed ofthe substrate.

In the fourteenth exposure apparatus in the present invention, theadjustment unit can adjust the exposure conditions based on adjustmentinformation on exposure conditions corresponding to a supply amount ofthe liquid by the supply mechanism.

According to a fifteenth aspect of the present invention, there isprovided a fifteenth exposure apparatus that illuminates a pattern withan energy beam and transfers the pattern onto a substrate via aprojection optical system, the exposure apparatus comprising: asubstrate stage on which the substrate is mounted that moves within atwo-dimensional plane holding the substrate; a supply mechanism thatsupplies liquid to a space between the projection optical system and thesubstrate on the substrate stage; a recovery mechanism that recovers theliquid; and a liquid removal mechanism that removes the liquid whichcould not be recovered by the recovery mechanism.

In this exposure apparatus, the supply mechanism supplies the liquid tothe space between the projection optical system and the substrate on thesubstrate stage, and the recovery mechanism recovers the liquid. In thiscase, a predetermined amount of liquid is held (filled) between (the tipof) the projection optical system and the substrate on the substratestage. Accordingly, when exposure (pattern transfer on the substrate) isperformed in this state, the immersion method is applied, and thewavelength of the exposure light on the surface of the substrate can beshortened 1/n times (n is the refractive index of the liquid) thewavelength in the air and furthermore the depth of focus is broadenedaround n times the depth of focus in the air. In addition, when theliquid supply by the supply mechanism and the liquid recovery by therecovery mechanism are performed in parallel, the liquid between theprojection optical system and the substrate is exchanged constantly. Inaddition, for example, in the case a situation occurs where the liquidcould not be completely recovered by the recovery mechanism, the liquidremoval mechanism removes the liquid that could not be recovered.

According to a sixteenth aspect of the present invention, there isprovided a sixteenth exposure apparatus that illuminates a pattern withan energy beam and transfers the pattern onto a substrate via aprojection optical system and liquid while locally holding the liquid onan image plane side of the projection optical system, the exposureapparatus comprising: a substrate stage on which the substrate ismounted that moves within a two-dimensional plane holding the substrate;a supply mechanism that supplies the liquid to an image plane side ofthe projection optical system; a first recovery mechanism that recoversthe liquid outside a projection area of the projection optical system;and a second recovery mechanism that recovers the liquid outside thefirst recovery mechanism with respect to the projection area.

The projection area of the projection optical system, in this case,means a projection area of an object such as a pattern image projectedby the projection optical system.

In this exposure apparatus, the supply mechanism supplies the liquid tothe image plane side of the projection optical system, and the firstrecovery mechanism recovers the liquid. In this case, the energy beamirradiates the pattern in a state where the liquid is held locally onthe image plane side of the projection optical system, and the patternis transferred on the substrate via the projection optical system andthe liquid. That is, immersion exposure is performed. Accordingly, thewavelength of the exposure light on the surface of the substrate can beshortened 1/n times (n is the refractive index of the liquid) thewavelength in the air and furthermore the depth of focus is broadenedaround n times the depth of focus in the air. In addition, in the case asituation occurs where the liquid could not be completely recovered bythe first recovery mechanism, the second recovery mechanism, which islocated on the outer side of the first recovery mechanism, collects theliquid that could not be recovered.

According to a seventeenth aspect of the present invention, there isprovided a seventeenth exposure apparatus that illuminates a patternwith an energy beam and transfers the pattern onto a substrate via aprojection optical system and liquid while locally holding the liquid onan image plane side of the projection optical system, the exposureapparatus comprising: a substrate stage on which the substrate ismounted that moves within a two-dimensional plane holding the substrate,wherein the substrate stage has a flat section which is substantiallyflush with a surface of the substrate in the periphery of the substrateheld on the substrate stage.

In this exposure apparatus, the energy beam illuminates the pattern in astate where the liquid is held locally on the image plane side of theprojection optical system, and the pattern is transferred on thesubstrate via the projection optical system and the liquid. That is,immersion exposure is performed. In addition, for example, even when thesubstrate stage moves to a position where the substrate is away from theprojection area of the projection optical system in a state where theliquid is held between the projection optical system and the substrateon the image plane side of the projection optical system, such as whenexposing the periphery on the substrate, or when the substrate on thesubstrate stage is exchanged after exposure has been completed, theliquid can be held between the projection optical system and the flatsection provided around the substrate held on the substrate stage, andthe liquid can be kept from flowing out.

According to an eighteenth aspect of the present invention, there isprovided an eighteenth exposure apparatus that illuminates a patternwith an energy beam and transfers the pattern onto a substrate via aprojection optical system and liquid while locally holding the liquid onan image plane side of the projection optical system, the exposureapparatus comprising: a substrate stage on which the substrate ismounted that moves within a two-dimensional plane holding the substrate,wherein the substrate stage has a flat section substantially flush witha surface of the substrate held on the substrate stage, and whenexposure operation on the substrate is suspended, the projection opticalsystem and the flat section face each other to keep on holding theliquid on the image plane side of the projection optical system.

In this exposure apparatus, the energy beam illuminates the pattern in astate where the liquid is held locally on the image plane side of theprojection optical system, and the pattern is transferred on thesubstrate via the projection optical system and the liquid. That is,immersion exposure is performed. In addition, when exposure operation ofthe substrate is not performed, the projection optical system and theflat section provided on the substrate stage can be arranged to faceeach other to keep on holding the liquid on the image plane side of theprojection optical system, so that for example, when a plurality ofsubstrates are continuously exposed, the liquid can be held on the imageplane side of the projection optical system while the substrate isexchanged and exposure can begin as soon as the substrate exchange iscompleted, without waiting for the liquid to be supplied. In addition,because the liquid is held on the image plane side of the projectionoptical system, it can prevent water marks or the like from beinggenerated on the tip surface on the image plane side of the projectionoptical system due to the tip surface drying up.

According to a nineteenth aspect of the present invention, there isprovided a nineteenth exposure apparatus that illuminates a pattern withan energy beam and transfers the pattern onto a substrate via aprojection optical system and liquid while locally holding the liquid onan image plane side of the projection optical system, the exposureapparatus comprising: a substrate stage on which the substrate ismounted that moves within a two-dimensional plane holding the substrate,wherein the substrate stage has a flat section substantially flush witha surface of the substrate held on the substrate stage, and afterexposure of the substrate held on the substrate stage has beencompleted, the substrate stage is moved to a predetermined positionwhere the liquid on an image plane side of the projection optical systemis recovered, and the substrate on which exposure has been completed isunloaded from the substrate stage, after recovery of the liquid has beencompleted.

In this exposure apparatus, the energy beam illuminates the pattern in astate where the liquid is held locally on the image plane side of theprojection optical system, and the pattern is transferred on thesubstrate via the projection optical system and the liquid. That is,immersion exposure is performed. In addition, after the exposure of thesubstrate held on the substrate stage has been completed, the substratestage is moved to the predetermined position, and the liquid on theimage plane side of the projection optical system is recovered. When thesubstrate stage is moved to the predetermined position, even in the casewhen the substrate stage moves to a position where the substrate is awayfrom the projection area of the projection optical system, the liquidcan be held between the projection optical system and the flat sectionprovided on the substrate stage. In addition, the predetermined positionmay be set to a position where the liquid is held with the projectionoptical system and the flat section provided on the substrate stagefacing each other. In any case, the liquid is recovered after thesubstrate stage moves to the predetermined position, and when the liquidrecovery is completed, then the substrate for which the exposure hasbeen finished is unloaded from the substrate stage.

According to a twentieth aspect of the present invention, there isprovided a twentieth exposure apparatus that illuminates a pattern withan energy beam and transfers the pattern onto a substrate via aprojection optical system and liquid while locally holding the liquid onan image plane side of the projection optical system, the exposureapparatus comprising: a supply mechanism that supplies the liquid to animage plane side of the projection optical system; and an exhaustmechanism that exhausts gas on an image plane side of the projectionoptical system, wherein the supply mechanism begins supplying the liquidin parallel with exhausting operation of the exhaust mechanism.

In this exposure apparatus, the energy beam illuminates the pattern in astate where the liquid is held locally on the image plane side of theprojection optical system, and the pattern is transferred on thesubstrate via the projection optical system and the liquid. That is,immersion exposure is performed. In addition, because the liquid supplyby the supply mechanism to the image plane side of the projectionoptical system begins in parallel with the exhaust of gas within thespace on the image plane side of the projection optical system, thespace can be filled smoothly with the liquid, and such an operation canalso prevent inconvenient bubbles and gas voids from remaining on theimage plane side of projection optical system.

According to a twenty-first aspect of the present invention, there isprovided a twenty-first exposure apparatus that irradiates an energybeam on a substrate via a projection optical system and liquid andexposes the substrate, the exposure apparatus comprising: a substratestage that is movable within a two-dimensional plane holding thesubstrate; and a control unit that controls movement of the substratestage based on at least one of temperature information of the liquid andpressure information of the liquid.

In this exposure apparatus, the energy beam is irradiated on thesubstrate via the projection optical system and the liquid, and thesubstrate is exposed. That is, immersion exposure is performed. Inaddition, because the control unit controls the movement of thesubstrate stage based on at least one of temperature information of theliquid and pressure information of the liquid, defocus or the like,which is generated during exposure due to temperature change of thewater in between the projection optical system and the substrate as wellas pressure of the water, can be effectively suppressed, and degradingin the transfer accuracy can be prevented.

In addition, in a lithographic process, by transferring a device patternon a substrate using any one of the first to the twenty-first exposureapparatus in the present invention, the pattern can be formed on thesubstrate with good accuracy, which allows production of a higherintegrated microdevices with good yield. Accordingly, further fromanother aspect of the present invention, it can be said that the presentinvention is a device manufacturing method that uses any one of thefirst to the twenty-first exposure apparatus in the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings;

FIG. 1 is an entire view of an arrangement of an exposure apparatusrelated to a first embodiment in the present invention;

FIG. 2 is a perspective view of a Z tilt stage and a wafer holder;

FIG. 3 is a sectional view of a liquid supply/drainage unit shown alongwith the lower end section of a barrel and a piping system;

FIG. 4 is a section view of line B-B in FIG. 3;

FIG. 5 is a view for describing a focal position detection system;

FIG. 6 is a block diagram that shows a partly omitted arrangement of acontrol system of the exposure apparatus in the first embodiment;

FIGS. 7A and 7B are views for describing the reasons why aberrationsoccur in an irradiation area on a wafer by irradiation of anillumination light;

FIG. 8A is a view showing a state of a wafer stage when it has moved toa liquid supply position, FIG. 8B is a view showing an example of apositional relation between a wafer stage and a projection unit in astep-and-scan exposure operation for a wafer, and FIG. 8C is a viewshowing a state of a wafer stage when it has moved to a liquid drainageposition;

FIG. 9 is a view showing a state of the inside of the liquidsupply/drainage unit filled with a desired depth of water;

FIG. 10A is a simplified view of the vicinity of liquid supply/drainageunit upon exposure of a first shot, and FIG. 10B is a simplified view ofthe vicinity of liquid supply/drainage unit when a wafer is scanned in adirection opposite to FIG. 10A;

FIGS. 11A to 11F are views that show a flow of a supply/drainageoperation in an exposure apparatus related to a second embodiment when awafer stage is scanned to expose a shot area;

FIG. 12 is a view for describing the case when an edge shot on a waferis exposed with the exposure apparatus in the second embodiment thatemploys a liquid supply/drainage unit related to a modified example inwhich a plurality of partitions are provided extending in parallel witha scanning direction;

FIGS. 13A to 13F are views for describing a modified example of thesecond embodiment that show a flow of a supply/drainage operation when awafer stage is scanned to expose a shot area;

FIGS. 14A and 14B each show a modified example of the liquidsupply/drainage unit;

FIG. 15 is a view of a modified example of liquid recovery via a holeprovided in a part of a projection lens;

FIG. 16 is a flow chart for explaining an embodiment of a devicemanufacturing method according to the present invention; and

FIG. 17 is a flow chart for showing a process in step 204 in FIG. 16.

DESCRIPTION OF THE EMBODIMENTS First Embodiment

A first embodiment of the present invention is described below,referring to FIGS. 1 to 10B.

FIG. 1 is an entire view of an arrangement of an exposure apparatus 100related to the first embodiment. Exposure apparatus 100 is a projectionexposure apparatus, based on a step-and-scan method (the so-calledscanning stepper). Exposure apparatus 100 comprises an illuminationsystem 10, a reticle stage RST that holds a reticle R serving as a mask,a projection unit PU, a stage unit 50 that includes a Z tilt stage 30 onwhich a wafer W serving as a substrate is mounted, a control system forsuch parts, and the like.

As is disclosed in, for example, Japanese Patent Application Laid-openNo. H06-349701 and its corresponding U.S. Pat. No. 5,534,970, thearrangement of illumination system 10 includes parts such as a lightsource, an illuminance uniformity optical system that includes anoptical integrator or the like, abeam splitter, a relay lens, a variableND filter, a reticle blind (none of which are shown). In illuminationsystem 10, an illumination light (exposure light) IL serving as anenergy beam illuminates a slit-shaped illumination area set by thereticle blind on reticle R where the circuit pattern or the like isfabricated with substantially uniform illuminance. As illumination lightIL, the ArF excimer laser beam (wavelength: 193 nm) is used as anexample. As illumination light IL, far ultraviolet light such as the KrFexcimer laser beam (wavelength: 248 nm) or bright lines in theultraviolet region generated by an ultra high-pressure mercury lamp(such as the g-line or the i-line) can also be used. In addition, as theoptical integrator, parts such as a fly-eye lens, a rod integrator (aninternal reflection type integrator), or a diffraction optical elementcan be used. As long as the national laws in designated states orelected states, to which this international application is applied,permit, the disclosure of U.S. Patent cited above is fully incorporatedherein by reference.

In addition, on the optical path of illumination light IL withinillumination system 10, a beam splitter is disposed that has a hightransmittance and a fairly low reflectivity, and on the optical path ofthe light reflected off the beam splitter, an integrator senor (opticalsensor) 14 is disposed, which is made up of a photoelectric conversionelement (not shown in FIG. 1, refer to FIG. 6). The photoelectricconversion signals of integrator sensor 14 are supplied to a maincontroller 20 (refer to FIG. 6).

On reticle stage RST, reticle R is fixed, for example, by vacuumsuction. Reticle stage RST is structured finely drivable in an XY planeperpendicular to the optical axis of illumination system 10 (coincidingwith an optical axis AX of a projection optical system PL, which will bedescribed later) by a reticle stage drive section 11 (not shown in FIG.1, refer to FIG. 6) that comprises parts such as a linear motor. It isstructured also drivable in a predetermined scanning direction (in thiscase, a Y-axis direction) at a designated scanning speed.

The position of reticle stage RST within the moving plane of the stageis detected at all times with a reticle laser interferometer(hereinafter referred to as a ‘reticle interferometer’) 16 via a movablemirror 15, at a resolution, for example, around 0.5 to 1 nm. In actual,on reticle stage RST, a movable mirror that has a reflection surfaceorthogonal to the Y-axis direction and a movable mirror that has areflection surface orthogonal to an X-axis direction are provided, andcorresponding to these movable mirrors, a reticle Y interferometer and areticle X interferometer are provided; however in FIG. 1, such detailsare representatively shown as movable mirror 15 and reticleinterferometer 16. Incidentally, for example, the edge surface ofreticle stage RST may be polished in order to form a reflection surface(corresponds to the reflection surface of movable mirror 15). Inaddition, instead of the reflection surface that extends in the X-axisdirection used for detecting the position of reticle stage RST in thescanning direction (the Y-axis direction in this embodiment), at leastone corner cubic mirror (such as a retroreflector) may be used. Of theinterferometers reticle Y interferometer and reticle X interferometer,one of them, such as reticle Y interferometer, is a dual-axisinterferometer that has two measurement axes, and based on themeasurement values of reticle Y interferometer, the rotation of reticlestage RST in a θz direction (the rotational direction around a Z-axis)can be measured in addition to the Y position of reticle stage RST.

The positional information on reticle stage RST from reticleinterferometer 16 is sent to main controller 20, via a stage controlunit 19. Stage control unit 19 drives and controls reticle stage RST viareticle stage drive section 11, based on the positional information ofreticle stage RST, in response to instructions from main controller 20.

Projection unit PU is disposed below reticle stage RST, as in FIG. 1.Projection unit PU comprises a barrel 40, and projection optical systemPL, which is made up of a plurality of optical elements, or to be morespecific, a plurality of lenses (lens elements) that share the sameoptical axis AX in the Z-axis direction, held at a predeterminedpositional relationship within the barrel. As projection optical systemPL, for example, a both-side telecentric dioptric system that has apredetermined projection magnification (such as ¼ or ⅕ times) is used.Therefore, when illumination light IL from illumination system 10illuminates the illumination area on reticle R, illumination light ILthat has passed through reticle R forms a reduced image of the circuitpattern within the illumination area on reticle R (a partial reducedimage of the circuit pattern) on wafer W whose surface is coated with aresist (photosensitive agent), via projection unit PU (projectionoptical system PL).

In addition, although it is omitted in the drawings, among the pluralityof lenses making up projection optical system PL, a plurality ofspecific lenses operate under the control of an image forming qualitycorrection controller 81 (refer to FIG. 6) based on instructions frommain controller 20, so that optical properties (including image formingquality) such as magnification, distortion, coma, and curvature of imageplane (including inclination of image plane), and the image planeposition can be adjusted.

Image forming quality correction controller 81 may adjust the quality ofthe image projected via projection optical system PL by moving reticle Ror by finely adjusting the wavelength of illumination light IL, or bycombining both ways as appropriate.

In addition, because exposure is performed using exposure apparatus 100of the embodiment to which the immersion method (to be described later)is applied, in the vicinity of a lens 42 (refer to FIG. 3) serving as anoptical element that constitutes projection optical system PL locatedclosest to the image plane (wafer W), a liquid supply/drainage unit 32is attached so that it surrounds the tip of barrel 40, which holds thelens. Details on liquid supply/drainage unit 32 and the arrangement ofthe piping system connected to the unit and the like will be described,later in the description.

Stage unit 50 comprises parts such as a wafer stage WST serving as asubstrate stage, a wafer holder 70 provided on wafer stage WST, and awafer stage drive section 24 which drives wafer stage WST and waferholder 70. As is shown in FIG. 1, wafer stage WST is disposed belowprojection optical system PL on a base (not shown). Wafer stage WSTcomprises an XY stage 31, which is driven in the XY direction by linearmotors or the like (not shown) constituting wafer stage drive section24, and Z tilt stage 30, which is mounted on XY stage 31 and is finelydriven in the Z-axis direction and in an inclination direction withrespect to the XY plane (the rotational direction around the X-axis (θxdirection) and the rotational direction around the Y-axis (θydirection)) by a Z tilt drive mechanism (not shown) that alsoconstitutes wafer stage drive section 24. And, on Z tilt stage 30, waferholder 70, which holds wafer W, is mounted.

As is shown in the perspective view in FIG. 2, in the peripheral portionof the area where wafer W is mounted (the circular area in the center),wafer holder 70 comprises a main body section 70A that has a specificshape where two corners located on one of the diagonal lines of asquare-shaped Z tilt stage 30 are projecting and the remaining twocorners located on the remaining diagonal line are shaped in quarterarcs of a circle one size larger that the circular area described above,and four auxiliary plates 22 a to 22 d arranged in the periphery of thearea where wafer W is to be mounted so that they substantially match theshape of main body section 70A. The surface (flat portion) of suchauxiliary plates 22 a to 22 d are arranged so that they aresubstantially the same height as the surface of wafer W (the heightdifference between the auxiliary plates and the wafer is to be around 1mm or under).

As is shown in FIG. 2, a gap D is formed between auxiliary plates 22 ato 22 d and wafer W, respectively, and the size of gap D is set ataround 3 mm or under. In addition, wafer W also has a notch (a V-shapednotch); however, since the size of the notch is around 1 mm, which issmaller than gap D, it is omitted in the drawings.

In addition, a circular opening is formed in auxiliary plate 22 a, and afiducial mark plate FM is tightly embedded in the opening. Fiducial markplate FM is arranged so that its surface is co-planar with auxiliaryplate 22 a. On the surface of fiducial mark plate FM, various types offiducial marks (none of which are shown) are formed that are used formeasurement operations such as reticle alignment or baseline measurementby the alignment detection system (to be described later). Auxiliaryplates 22 a to 22 d do not necessarily have to be plate-shaped, and theupper surface of Z tilt stage 30 may be arranged so that it becomesalmost the same height as wafer W. The point is to form a flat portionin the periphery of wafer W at substantially the same height as thesurface of wafer W.

Referring back to FIG. 1, XY stage 31 is structured movable not only inthe scanning direction (the Y-axis direction) but also in a non-scanningdirection (the X-axis direction) perpendicular to the scanning directionso that the shot areas serving as a plurality of divided areas on waferW can be positioned at an exposure area conjugate with the illuminationarea. And, XY stage 31 performs a step-and-scan operation in which anoperation for scanning exposure of each shot area on wafer W and anoperation (movement operation performed between divided areas) formoving wafer W to the acceleration starting position (scanning startingposition) to expose the next shot are repeated.

The position of wafer stage WST within the XY plane (including rotationaround the Z-axis (θz rotation)) is detected at all times by a waferlaser interferometer (hereinafter referred to as ‘wafer interferometer’)18 via a movable mirror 17 provided on the upper surface of Z tilt stage30, at a resolution, for example, around 0.5 to 1 nm. In actual, on Ztilt stage 30, for example, as is shown in FIG. 2, a Y movable mirror17Y that has a reflection surface orthogonal to the scanning direction(the Y-axis direction) and an X movable mirror that has a reflectionsurface orthogonal to the non-scanning direction (the X-axis direction)are provided, and corresponding to these movable mirrors, as the waferinterferometers, an X interferometer that irradiates an interferometerbeam perpendicularly on X movable mirror 17X and a Y interferometer thatirradiates an interferometer beam perpendicularly on Y movable mirror17Y are provided; however, such details are representatively shown asmovable mirror 17 and wafer interferometer 18 in FIG. 1. Incidentally,the X interferometer and the Y interferometer of wafer interferometer 18are both multi-axis interferometers that have a plurality of measurementaxes, and with these interferometers, other than the X and Y positionsof wafer stage WST (or to be more precise, z tilt stage 30), rotation(yawing (θz rotation, which is rotation around the Z-axis), pitching (θxrotation, which is rotation around the X-axis), and rolling (θyrotation, which is rotation around the Y-axis) can also be measured.And, for example, the edge surface of Z tilt stage 30 may be polished inorder to form a reflection surface (corresponds to the reflectionsurface of movable mirrors 17X and 17Y). In addition, the multi-axisinterferometers may detect positional information related to the opticalaxis direction (the Z-axis direction) of projection optical system PL,by irradiating a laser beam on a reflection surface provided on theframe on which projection optical system PL is mounted (not shown), viaa reflection surface arranged on Z tilt stage 30 at an inclination of45°.

Positional information (or velocity information) on wafer stage WST issent to stage control unit 19, and then to main controller 20 via stagecontrol unit 19. Stage control unit 19 controls wafer stage WST viawafer stage drive section 24 based on the positional information (orvelocity information) on wafer stage WST referred to above, in responseto instructions from main controller 20.

Next, details on liquid supply/drainage unit 32 will be described,referring to FIGS. 3 and 4. FIG. 3 shows a sectional view of liquidsupply/drainage unit 32, along with the lower end section of barrel 40and the piping system. In addition, FIG. 4 shows a sectional view ofline B-B in FIG. 3. Liquid supply/drainage unit 32 is configured to bedetachable to barrel 40; therefore, in the case inconveniences such asmalfunction or damage occur, it can be exchanged.

As is shown in FIG. 3, on the end of the image plane side of barrel 40of projection unit PU (the lower end section), a small diameter section40 a is formed whose diameter is smaller than other sections, and thetip of small diameter section 40 a is shown as tapered section 40 bwhose diameter becomes smaller the lower it becomes. In this case,within small diameter section 40 a, lens 42 is held, which is one of thelenses structuring projection optical system PL located closest to theimage plane. The lower surface of lens 42 is to be parallel to the XYplane orthogonal to optical axis AX.

Liquid supply/drainage unit 32 has a stepped cylindrical shape whenviewed from the front (and the side), and in the center, an opening 32 athat has a circular section into which small diameter section 40 a ofbarrel 40 can be inserted from above is formed in a vertical direction.The diameter of opening 32 a (the diameter of the inner circumferentialsurface of a ring-shaped side wall 32 c, which makes the aperture on theouter side) is constant from the upper end to the vicinity of the lowerend, and when it becomes lower it is tapered, or in other words, thediameter becomes smaller. As a consequence, with the outer surface oftapered section 40 b of barrel 40 a and the inner surface of ring-shapedside wall 32 c, a kind of a nozzle (hereinafter referred to as a‘tapered nozzle section’ for the sake of convenience) is formed thatwidens when viewed from above (narrows when viewed from below).

On the lower end surface of liquid supply/drainage unit 32, a depressedsection 32 b in the shape of a ring when viewed from below is formed onthe outer side of opening 32 a. In this case, ring-shaped side wall 32 cthat has a predetermined wall thickness is formed between depressedsection 32 b and opening 32 a. The lower end surface of ring-shaped sidewall 32 c is arranged to be co-planar with the lower surface of lens 42(the lowest end surface of barrel 40). The diameter of the outerperiphery surface of ring-shaped side wall 32 c is constant from theupper end to the vicinity of the lower end, and below the vicinity ofthe lower end, it has a tapered shape that narrows when it nears thebottom.

As is obvious from FIGS. 3 and 4, between ring-shaped side wall 32 c andsmall diameter section 40 a of barrel 40, a space is formed that isshaped in a ring in a planar view (when viewed from above or below). Inthis space, one end of a plurality of recovery pipes 52 is inserted inthe vertical direction spaced almost equally apart around the entirecircumference.

On the bottom (upper) surface of depressed section 32 b referred toabove of liquid supply/drainage unit 32, through holes 34 are formed,respectively, in the vertical direction, on both sides of ring-shapedside wall 32 c in the X-axis direction and the Y-axis direction, andinto each through hole 34, one end of exhaust pipes 54 is inserted(through hole 54 located on both sides in the X-axis direction are notshown in FIG. 3, refer to FIG. 4). In addition, on the bottom (upper)surface of depressed section 32 b of liquid supply/drainage unit 32,circular holes are formed at a plurality of places (for example, twoplaces), and the lower end section of full recovery nozzles 56 areinserted into the circular holes, respectively.

Furthermore, on the lower end of liquid supply/drainage unit 32, on theouter side of depressed section 32 b, a depressed groove 32 d, which hasa ring shape when viewed from below, is formed. In this case, aring-shaped side wall 32 e that has a predetermined wall thickness isformed between depressed groove 32 d and depressed section 32 b. Thelower end surface of ring-shaped side wall 32 e is arranged to beco-planar with the lower surface of lens 42 (the lowest end surface ofbarrel 40). The diameter of the inner periphery surface of ring-shapedside wall 32 e is constant from the upper end to the lower end while theouter periphery surface is constant from the upper end to the vicinityof the lower end, and below the vicinity of the lower end, it has atapered shape that narrows when it nears the bottom.

The depth of depressed groove 32 d is configured to be somewhat smaller(a predetermined distance) than depressed section 32 b, and on thebottom (upper) surface of depressed groove 32 d of liquidsupply/drainage unit 32, a plurality of stepped through holes are formedarranged at a predetermined spacing. Into each of the through holes, oneend of each of supply pipes 58 is inserted from above, and the smalldiameter section at the lower end of each of the through holes isreferred to as a supply nozzle 36.

The wall on the outer side of depressed groove 32 d referred to above ofliquid supply/drainage unit 32, or in other words, a peripheral wall 32f may be referred to as a projected section 32 g, since a portion of theinner periphery of peripheral wall 32 f projects downward apredetermined distance ΔH when compared with the remaining portion. Thelower end surface of projected section 32 g is parallel to the lowersurface of lens 42, and the clearance between wafer W and its surface,that is clearance Δh is 3 mm and under, for example, around 1 to 2 mm.In addition, in this case, the surface of the tip of projected section32 g is positioned approximately ΔH lower than that of lens 42.

The diameter of the lower end of inner periphery of peripheral wall 32 f(the vicinity of projected section 32 g) becomes larger as it nears thebottom, having a tapered shape. As a consequence, by the walls (32 e and32 f (32 g)) on both sides that constitute depressed groove 32 d, a kindof a nozzle (hereinafter referred to as a ‘widened nozzle section’ forthe sake of convenience) is formed that widens when viewed from above(narrows when viewed from below).

In a ring shaped area on the outer side of projected section 32 g ofperipheral wall 32 f, on both sides in the X-axis direction as well asthe Y-axis direction, two pairs of arcuate slits that have apredetermined depth, slits 32 h 1 and 32 h 2, and slits 32 h 3 and 32 h4 are formed. The width of each slit is considerably small compared withdepressed groove 32 d, so that a capillary phenomenon could occur withinthe slit. Intake holes that communicate with the slits 32 h ₁ and 32 h₂, and slits 32 h ₃ and 32 h ₄, respectively, which are circular holeswhose diameter is slightly larger than that of the slits 32 h ₁ and 32 h₂, and slits 32 h ₃ and 32 h ₄, are formed on the upper surface ofliquid supply/drainage unit 32, with at least one intake holecorresponding to each slit, and to each intake hole, one end ofauxiliary recovery pipes 60 is inserted (in FIG. 3, however, auxiliaryrecovery pipes 60 ₁ and 60 ₂ that communicate with slits 32 h ₁ and 32 h₂ located on both sides in the X-axis direction are not shown (refer toFIG. 4), and only auxiliary recovery pipes 60 ₃ and 60 ₄ thatcommunicate with slits 32 h ₃ and 32 h ₄ located on both sides in theY-axis direction are shown).

The other end of each of the supply pipes 58 connects to a supply pipeline 64, which has one end connecting to a liquid supply unit 72 and theother end connecting to supply pipes 58, respectively, via valves 62 a.Liquid supply unit 72 includes parts such as a liquid tank, a pressurepump, and a temperature control unit, and operates under the control ofmain controller 20. In this case, when liquid supply unit 72 is operatedin a state where the corresponding valve 62 a is open, for example, apredetermined liquid used for immersion whose temperature is controlledso that it is about the same temperature as that in a chamber (drawingomitted) where (the main body of) exposure apparatus 100 is housed issupplied via supply nozzle 36, to a substantially closed spacepartitioned by liquid supply/drainage unit 32 and the surface of waferW. Hereinafter, valves 62 a provided in each of the supply pipes 58 mayalso be considered together and referred to as a valve group 62 a (referto FIG. 6).

As the liquid referred to above, in this case, ultra pure water(hereinafter, it will simply be referred to as ‘water’ besides the casewhen specifying is necessary) that transmits the ArF excimer laser beam(light with a wavelength of 193.3 nm) is to be used. Ultra pure watercan be obtained in large quantities at a semiconductor manufacturingplant or the like, and it also has an advantage of having no adverseeffect on the photoresist on the wafer or to the optical lenses. Inaddition, ultra pure water has no adverse effect on the environment aswell as an extremely low concentration of impurities, therefore,cleaning action on the surface of the wafer and the surface of lens 42can be anticipated.

Refractive index n of the water is said to be around 1.44 to 1.47, andin the water the wavelength of illumination light IL shortens to 193nm×1/n=around 131 to 134 nm.

The other end of each of the recovery pipes 52 connects to a recoverypipe line 66, which has one end connecting to a liquid recovery unit 74and the other end connecting to recovery pipes 52, respectively, viavalves 62 b. Liquid recovery unit 74 includes parts such as a liquidtank, and a suction pump, and operates under the control of maincontroller 20. In this case, when the corresponding valve 62 b is in anopened state, liquid recovery unit 74 recovers the water in thesubstantially closed space referred to earlier via each of the recoverypipes 52. Hereinafter, valves 62 b provided in each of the recoverypipes 52 may also be considered together and referred to as a valvegroup 62 b (refer to FIG. 6).

The upper end of each of the full recovery nozzles 56 referred toearlier connect to recovery pipe line 66 referred to above, via a jointrecovery pipe line 68 and a shared valve 62 c. In this case, each fullrecovery nozzle 56 is configured to be vertically movable by a drivemechanism 63 (not shown in FIG. 3, refer to FIG. 6), which operatesunder the control of main controller 20. And, each full recovery nozzle56 is configured to be movable by a predetermined distance lower thanthe surface of wafer W. Therefore, when valve 62 c is in an openedstate, by lowering all the full recovery nozzles 56 to a positionsubstantially the same height as the wafer surface, liquid recovery unit74 completely recovers the water on the wafer (or the auxiliary plates22 a to 22 d referred to earlier) via all the full recovery nozzles 56.

The other end of each of the exhaust pipes 54 connects to a vacuumpiping system 69, which has one end connecting to a vacuum exhaust unit76 that incorporates a vacuum pump as a suction mechanism and the otherend connecting to exhaust pipes 54, respectively, via valves 62 d.Vacuum exhaust unit 76 operates under the control of main controller 20.Hereinafter, valves 62 d provided in each of the exhaust pipes 54 mayalso be considered together and referred to as a valve group 62 d (referto FIG. 6).

In addition, auxiliary recovery pipes 60 ₁ to 60 ₄ referred to earlierconnect to vacuum piping system 69, respectively, via a shared valve 62e. In this case, in the situation where all the valves 62 d are open andvacuum exhaust unit 76 is operating, when the water is filled up (referto FIG. 8) to a position above the lower end surface of lens 42 on waferW (or the auxiliary plates 22 a to 22 d referred to earlier), it createsnegative pressure in the upper space of depressed section 32 b, whichraises the water level.

In addition, in the case where valve 62 e is in an opened state andvacuum exhaust unit 76 is operating, for example, when the water leaks(flows out) outside peripheral wall 32 f referred to earlier, the wateris sucked up into the slits (any of slits 32 h ₁ to 32 h ₄) due tocapillary phenomenon as well as by the vacuum suction force of vacuumexhaust unit 76, and exhausted outside.

As the valves referred to above, adjustment valves (such as a flowcontrol valve) or the like that open and close, and whose opening canalso be adjusted are used. These valves operate under the control ofmain controller 20 (refer to FIG. 6).

On the upper surface of liquid supply/drainage unit 32, holes are formedin a vertical direction toward the bottom (upper) surface of depressedsection 32 b at a plurality of points, and liquid supply/drainage unit32 is fixed to the bottom section of barrel 40 with screws 80 via suchholes, respectively (refer to FIG. 4).

In addition, on both sides of tapered section 40 b of barrel 40 in theY-axis direction, a pair of temperature sensors 38A and 38B is fixed,respectively. The output of these temperature sensors is sent to maincontroller 20 (refer to FIG. 6).

In addition, as is shown in FIG. 3, in the vicinity of slits 32 h ₃ and32 h ₄, gas supply nozzles 853 and 854 are provided, respectively.Furthermore, although it is omitted in the drawings, in the vicinity ofslits 32 h 1 and 32 h 2, gas supply nozzles are also provided,respectively. The gas supply nozzles each connect to an air conditioningmechanism 86 (not shown in FIG. 3, refer to FIG. 6), which operatesunder the control of main controller 20.

In exposure apparatus 100 in the embodiment, a focal point detectionsystem is provided for the so-called auto-focusing and auto-leveling ofwafer W. The focal point detection system will be described below,referring to FIG. 5.

In FIG. 5, a pair of prisms 44A and 44B, which is made of the samematerial as lens 42 and arranged in close contact with lens 42, isprovided between lens 42 and tapered section 40 b of barrel 40.

Furthermore, in the vicinity of the lower end of a large diametersection 40 c, which is the section excluding small diameter section 40 aof barrel 40, a pair of through holes 40 d and 40 e is formed thatextends in the horizontal direction and communicates the inside ofbarrel 40 with the outside. On the inner side (the space side referredto earlier) end of such through holes 40 d and 40 e, right angle prisms46A and 46B are disposed, respectively, and fixed to barrel 40.

On the outside of barrel 40, an irradiation system 90 a is disposedfacing one of the through holes, 40 d. In addition, on the outside ofbarrel 40, a photodetection system 90 b that constitutes the focal pointdetection system with irradiation system 90 a is disposed, facing theother through hole, 40 e. Irradiation system 90 a has a light sourcewhose on/off is controlled by main controller 20 in FIG. 1, and emitsimaging beams in the horizontal direction so as to form a large numberof pinhole or slit images toward the imaging plane of projection opticalsystem PL. The emitted imaging beams are reflected off right angle prism46A vertically downward, and are irradiated on the surface of wafer Wfrom an oblique direction against optical axis AX by prism 44A referredto earlier. Meanwhile, the beams of the imaging beams reflected off thesurface of wafer W are reflected vertically upward by prism 44B referredto earlier, and furthermore, reflected in the horizontal direction byright angle prism 46B, and then received by photodetection system 90 b.As is described above, in the embodiment, the focal position detectionsystem is formed consisting of a multiple point focal position detectionsystem based on an oblique method similar to the one disclosed in, forexample, Japanese Patent Application Laid-open 06-283403 and thecorresponding U.S. Pat. No. 5,448,332, and the system includesirradiation system 90 a, photodetection system 90 b, prisms 44A and 44B,and right angle prisms 46A and 46B. The focal position detection systemwill be referred to as focal position detection system (90 a, 90 b) inthe following description. As long as the national laws in designatedstates or elected states, to which this international application isapplied, permit, the disclosures of the above publication and U.S.patent are fully incorporated herein by reference.

Defocus signals, which are an output of photodetection system 90 b offocal position detection system (90 a, 90 b), are sent to maincontroller 20.

Main controller 20 controls the movement of Z tilt stage 30 and waferholder 70 in the Z-axis direction and the inclination in atwo-dimensional direction (that is, rotation in the θx and θy direction)via stage control unit 19 and wafer stage drive section 24 when scanningexposure (to be described later) or the like is performed, based ondefocus signals such as the S-curve signal from photodetection system 90b so that defocus equals zero. That is, main controller 20 performsauto-focusing (automatic focusing) and auto-leveling in which theimaging plane of projection optical system PL and the surface of wafer Ware made to substantially coincide with each other within theirradiation area (the area optically conjugate with the illuminationarea described earlier) of illumination light IL, by controlling themovement of Z tilt stage 30 and wafer holder 70 using focal positiondetection system (90 a, 90 b). Details on this operation will bedescribed, later in the description.

FIG. 6 is a block diagram of an arrangement of a control system ofexposure apparatus 100, with the arrangement partially omitted. Thecontrol system is mainly composed of main controller 20, which is madeup of a workstation (or a microcomputer) or the like, and stage controlunit 19, which operates under the control of main controller 20.

Other than the sections described so far, main controller 20 connects toa memory 21. Within memory 21, the following information is stored:information for calculating water temperature distribution (for example,computation formula or table data) within the projection area of thepattern on wafer W referred to earlier optically conjugate with theillumination area of reticle R where illumination light IL isirradiated, or in other words, within the irradiation area on the waferwhere illumination light IL is irradiated via the pattern and projectionoptical system PL on exposure, based on temperature difference obtainedfrom the measurement results of temperature sensors 38A and 38B andinformation on the flow of water (flow speed and flow rate) under lens42 while scanning exposure is performed (to be described later);information (for example, computation formula or table data) forcalculating temperature change coefficients that corresponds to thechange in aberration (for example, best focus position, curvature ofimage plane(including inclination of image plane), spherical aberration,and the like) of the pattern image projected within the irradiationarea, and measurement errors of the focal position detection system (90a, 90 b) occurring due to the temperature distribution; and otherinformation. Such information is obtained in advance, based onsimulation results or the like.

The reason why an aberration change occurs in the pattern imageprojected on the irradiation area on wafer W by irradiating illuminationlight IL will be briefly described below with the inclination of theimage plane in the scanning direction as an example, referring to FIGS.7A and 7B.

FIG. 7A shows the temperature distribution (temperature contour) of thewater on wafer W when the water exists on wafer W and the relative speedbetween projection optical system PL and the water is zero, that is, ina state where wafer W rests and no water flow occurs, and wafer W isheated due to illumination light IL irradiating the irradiation area onwafer W. In FIG. 7A, reference letter C indicates a low temperaturesection and reference letter H indicates a high temperature section. Asis shown, when the temperature distribution of the water changes by theirradiation of illumination light IL, it becomes the cause of a changein the best focus position, and the cause of changes such as sphericalaberration, astigmatism, distortion, and the like in the pattern imageprojected within the irradiation area on wafer W. In this case, becausethe temperature distribution in the vicinity of the irradiation area issymmetrical, the best focus position of a point on one end in thescanning direction (the lateral direction of the page surface of FIG.7A), point P₁, and the best focus position of a point on the other endin the scanning direction, point P2, are at the same position,therefore, inclination of the image plane does not occur in the scanningdirection. The temperature distribution of the water is not limited tothe one shown in FIG. 7A, and there maybe a case where a temperaturechange occurs when illumination light IL is absorbed by the water, andthe temperature of the water near the tip of projection optical systemPL becomes higher than the temperature of the water close to the surfaceof wafer W.

Meanwhile, in a state where the relative speed between projectionoptical system PL and the water is not zero, for example, in the casethe water flows at a predetermined speed in a direction indicated by anarrow F in FIG. 7B, when the wafer is heated by illumination light ILirradiating the irradiation area on wafer W, the temperaturedistribution of the water on wafer W results as is shown in FIG. 7B.And, also in FIG. 7B, reference letter C indicates a low temperaturesection and reference letter H indicates a high temperature section. Inthis case, the temperature distribution of the water in the vicinity ofthe irradiation area is obviously asymmetrical. Therefore, when thisasymmetry of the temperature distribution is ignored, the best focusposition of the point P2 on the other end in the scanning direction (thelateral direction of the page surface of FIG. 7A) deviates to a point ΔZupward from the surface of wafer W, while the best focus position ofpoint P1 on the one end in the scanning direction coincides with thesurface of wafer W. The reason why the best focus position of point P2does not coincide with the surface of wafer W is because the waterheated by the heat from the wafer moves from point P₁ to point P₂. Inthis case, the closer it is to the upstream side (a position near pointP₁), cold water flowing from upstream is more dominant, whereas, thecloser it is to the downstream side (a position near point P₂), heatedwater is more dominant. When the temperature distribution is as shown inFIG. 7B, a difference occurs in the best focus position of point P₁ andpoint P₂ because temperature change (temperature distribution)corresponds to the change (distribution) in refractive index.Accordingly, in this sense, changes may also occur in other aberrations,spherical aberration, astigmatism, distortion, and the like,corresponding to the temperature distribution. As is previouslydescribed, because there may be a case where a temperature change occurswhen illumination light IL is absorbed by the water, and the temperatureof the water near the tip of projection optical system PL becomes higherthan the temperature of the water close to the surface of wafer W, thetemperature distribution of the water is not limited to the one shown inFIG. 7B.

As is obvious from the description above, aberration distribution (suchas, focus distribution) caused by the temperature distribution of thewater within the illumination area depends on the direction of the waterflow.

In addition, when there is a water flow between lens 42 and wafer Wpreviously described, pressure difference occurs between the upstreamand downstream sides. In other words, the pressure on the downstreamside is more negative compared with that on the upstream side. That is,the pressure of the water between projection optical system PL and waferW changes, and such pressure changes the position of lens 42 and waferW1 which then causes aberration corresponding to the position within theillumination area such as the change in the best focus position, orcauses control error in the auto-focus and auto-leveling. In addition,the pressure distribution in the scanning direction relates closely withthe speed of the water referred to above, and changes in accordance withthe scanning speed of wafer W, the supply quantity of the water(liquid), and the like.

Accordingly, within memory 21, table data (or computation formulas) isstored that include the scanning speed of the wafer and the supplyquantity of the water as data (or parameters), for calculating apressure change coefficient that corresponds to the change in aberration(such as best focus position, curvature of field (including inclinationof field), spherical aberration, and the like) within the irradiationarea. Such table data (or computation formulas) is obtained, based onthe results of simulation that has been performed in advance. Thepressure change coefficient also includes aberration change component,which corresponds to control error in the surface position of wafer W.

Within memory 21, formulas or the like for calculating the aberrationsreferred to above, which include temperature change coefficient andpressure change coefficient as parameters, are also stored.

A series of operations in the exposure process of exposure apparatus 100in the embodiment having the arrangement described above will bedescribed next, referring to FIGS. 8A to 10B.

As a premise, reticle R is to be loaded on reticle stage RST. Inaddition, wafer stage WST is to be positioned at the wafer exchangeposition, and wafer W is to be loaded on wafer holder 70.

Then, in the same manner as in a typical scanning stepper, preparatoryoperations, which are predetermined, are performed, such as reticlealignment, using a reticle alignment system (not shown), the alignmentdetection system, and fiducial mark plate FM previously described, andwafer alignment, as in baseline measurement of an alignment system (notshown) and EGA (Enhanced Global Alignment).

Then, when wafer alignment has been completed, main controller 20 thengives instructions to stage control unit 19, and moves wafer stage WSTto a predetermined water supply position. FIG. 8A shows a state wherewafer stage WST has been moved to the water supply position. In FIG. 8A,reference letter PU indicates the position of the tip of barrel 40 ofprojection unit PU. In the embodiment, the water supply position is setto a position where projection unit PU is positioned directly abovefiducial mark plate FM.

Next, main controller 20 starts the operation of liquid supply unit 72as well as opens valve group 62 a to a predetermined level, and beginsto supply water from all the supply nozzles 34. Then, immediatelyafterwards, main controller 20 starts the operation of vacuum exhaustunit 76 as well as completely open valve groups 62 d and 62 e, andbegins vacuum exhaust via each of the exhaust pipes 54 and auxiliaryrecovery pipes 60 ₁ to 60 ₄. In addition, during such operations, maincontroller 20 begins local air conditioning in the vicinity of liquidsupply/drainage unit 32, by controlling air conditioning mechanism 86.In this manner, by supplying the water into the space on the image planeside of projection optical system PL while exhausting the gas in thespace, not only can the water be filled smoothly in the space, but itcan also prevent inconvenient bubbles and gas voids from remaining onthe image plane side of projection optical system PL.

And, when a predetermined period of time elapses, the substantiallyclosed space partitioned by liquid supply/drainage unit 32 and thesurface of fiducial mark plate FM is filled with a predetermined amountof water. The water supply amount immediately after the water supplystarts is set to a low level so that the water does not leak outsidefrom a clearance (gap) formed between projected section 32 g ofperipheral wall 32 f and fiducial mark plate FM due to the force ofwater, and at the stage where the water is filled up to the height Δhand the inside of liquid supply/drainage unit 32 becomes a completelyclosed space, the water supply amount is set to a high level. Maincontroller 20 may perform such a setting of water supply amount byadjusting the degree of opening of each valve in valve group 62 a, or bycontrolling the water supply amount itself from liquid supply unit 72.Immediately after the water supply starts, the water supply amount maybe gradually increased, or increased step by step.

In any case, when the water supply reaches depth Δh, the spacepartitioned by liquid supply/drainage unit 32 and the surface of thewater becomes under negative pressure, which supports the weight of thewater, against the outside of liquid supply/drainage unit 32 due to thevacuum suction force of vacuum exhaust unit 76, that is, the negativepressure raises the water level. Accordingly, when the water supplyamount is increased after the water supply reaches depth Δh, the waterbecomes difficult to leak from the clearance formed under projectedsection 32 g of peripheral wall 32 f. In addition, in this case, becausethe clearance is around 1 to 2 mm, the water is also held withinperipheral wall 32 f (projected section 32 g) by its surface tension.

When the predetermined space between projection optical system PL andfiducial mark plate FM has been filled with liquid, main controller 20then gives instructions to stage control unit 19, and moves wafer stageWST so that the tip of projection unit PU is positioned at apredetermined position above wafer W. In the case wafer stage WST movesfrom the starting position of water supply shown in FIG. 8A, animmersion area under projection unit PU will pass through the border ofauxiliary plate 22 a and wafer W, however, since the surface ofauxiliary plate 22 a and the surface of wafer W are almost the sameheight and the gap between auxiliary plate 22 a and wafer W is around 1mm, the water held under lens 42 can be maintained.

When peripheral air is drawn into each of slits 32 h 1 to 32 h 4 byvacuum suction via slits 32 h 1 to 32 h 4 referred to earlier, in thecase no countermeasures are taken, it may cause air turbulence as wellas lower the pressure of the space on the lower side of each slit to anegative pressure, and when such negative pressure occurs, thepossibility of the water leaking from the clearance (gap) underprojected section 32 g of peripheral wall 32 f becomes higher. In theembodiment, however, air conditioning mechanism 86 referred to earliereffectively suppresses such air turbulence and negative pressure fromoccurring in the vicinity of each slit, via gas supply nozzles 85 ₃ and85 ₄ or the like.

FIG. 9 shows a state where the inside of liquid supply/drainage unit 32is filled with the water reaching a desired depth on wafer W, and theimmersion area is formed on a part of wafer W that includes theprojection area of projection optical system PL. And, exposureoperations based on a step-and-scan method are performed in the mannerdescribed below.

More specifically, under the instructions of main controller 20, stagecontrol unit 19 moves wafer stage WST via wafer stage drive section 24,based on wafer alignment results, to the acceleration starting positionfor exposure of the first shot area (first shot), which serves as afirst divided area on wafer W held on wafer holder 70. When wafer stageWST moves from the water supply position (liquid supply position) to theacceleration starting position referred to above, main controller 20starts the operation of liquid recovery unit 74 as well as opens atleast one valve 62 of valve group 62 b to a predetermined degree ofopening, and recovers the water inside liquid supply/drainage unit 32via recovery pipes 52. And on such operation, selection of valve 62 bused for the recovery of water and adjustment of the degree of openingin each valve 62 b are performed, so that the inside of liquidsupply/drainage unit 32 is filled with a constant amount of water at alltimes that makes the water surface higher than the lower surface of lens42.

In this case, main controller 20 may completely close valves 62 a thatcorrespond to supply nozzle 36, which are located at a position besidesthe rear side of projection unit PU in the moving direction of waferstage WST (wafer W) and open valves 62 b that correspond to recoverypipes 52, which are located at a position on the front side ofprojection unit PU in the moving direction, at a predetermined degree ofopening. This operation creates a water flow under lens 42 that movesfrom the rear side of projection unit PU to the front side, in the samedirection as the moving direction of wafer stage WST, while wafer stageWST is moving. And, also in this case, it is preferable for maincontroller 20 to set the supply amount and the recovery amount of thewater so that the inside of liquid supply/drainage unit 32 is alwaysfilled with a constant amount of water that makes the water surfacehigher than the lower surface of lens 42, while exchanging the waterconstantly.

When wafer W (wafer stage WST) has been moved to the accelerationstarting position described above, stage control unit 19 beginsrelatively scanning reticle-stage RST and wafer stage WST in the Y-axisdirection via reticle stage drive section 11 and wafer stage drivesection 24, in response to the instructions from main controller 20.And, when both stages, RST and WST, reach their target scanning speedand move into a constant speed synchronous state, illumination light IL(ultraviolet pulse light) from illumination system 10 begins toilluminate the pattern area of reticle R, and scanning exposure begins.Stage control unit 19 performs the relative scanning referred to above,in response to the instructions from main controller 20, by controllingreticle stage drive section 11 and wafer stage drive section 24 whilemonitoring the measurement values of wafer interferometer 18 and reticleinterferometer 16 previously described.

Stage control unit 19 performs synchronous control, especially duringscanning exposure described above, so that the Y-axis direction movingspeed Vr of reticle stage RST and the Y-axis direction moving speed Vwof wafer stage WST are maintained at a speed ratio corresponding to theprojection magnification of projection optical system PL.

Then, different areas in the pattern area of reticle R are sequentiallyilluminated by illumination light IL, and when the entire pattern areahas been illuminated, scanning exposure of the first shot is completed.By this operation, the pattern of reticle R is reduced and transferredonto the first shot via projection optical system PL.

On scanning exposure of the first shot on wafer W described above, inthe same manner as when wafer stage WST moves from the water supplyposition to the acceleration starting position described above, maincontroller 20 adjusts the degree of opening (including a fully closedstate and a fully opened state) of each valve constituting valve groups62 a and 62 b, so that a water flow is created under lens 42, that movesfrom the rear side of projection unit PU to the front side in thescanning direction, that is, the moving direction of wafer W, in thesame direction as the moving direction of wafer W (+Y direction).

FIG. 10A is a simplified view of the vicinity of liquid supply/drainageunit 32 at such a point. The direction of the water flow at this pointis the same as scanning direction SD of wafer W (+Y direction), and thewater flow speed is greater than the scanning speed of wafer W.Therefore, the water flows above wafer W from the left side to the rightside of the drawing, and the illumination area of illumination light ILon the surface of the wafer (the projection area of the pattern onreticle R via projection optical system PL) is always filled with apredetermined amount of water during the scanning exposure (the water isexchanged at all times).

In this case, the water may leak outside from the front side ofprojected section 32 g of peripheral wall 32 f in the scanningdirection, depending on the flow speed and flow rate of the water,however, the water that leaks out is sucked up into slit 32 h 3 due tocapillary phenomenon as well vacuum sucked by vacuum exhaust unit 76 viaauxiliary recovery pipes 60 ₃, and exhausted outside. That is, regardingthe scanning direction of wafer W, the liquid that could not berecovered by recovery pipes 52 provided on the opposite side of supplypipes 58 and spilled outside peripheral wall 32 g is recovered (removed)from wafer W by auxiliary recovery pipes 60 ₃.

In addition, as is shown in FIG. 10A, in the case bubbles are found inthe water supplied, or supposing that bubbles are generated just afterthe water supply is performed, because the space (negative pressurespace) described earlier is available on the upstream side of lens 42,bubbles are collected within the space so that they do not reach thearea underneath lens 42 when the relative speed of the water withrespect to wafer W does not exceed a certain value (normal usage state).That is, because bubbles in the water are collected between supply pipesand lens 42, they do not reach the area between lens 42 and wafer W,which means that the bubbles do not deteriorate the image of the patternprojected on wafer W.

Incidentally, a groove may be provided on the lower surface of lens 42in an unused space, that is, the space where exposure light does notpass. In this case, even if bubbles reach the area between lens 42 andwafer W, because the groove captures the bubbles, it can prevent thebubbles from reaching the optical path of the exposure light in a moresecure manner.

During the scanning exposure described above, because exposure needs tobe performed in a state where the illumination area on wafer Wsubstantially coincides with the imaging plane of projection opticalsystem PL, main controller 20 performs auto-focusing and auto-levelingin the manner described below, from a. to f., based on the output of thefocal position detection system (90 a, 90 b).

-   a. Main controller 20 takes in measurement values of temperature    sensors 38A and 38B during scanning exposure, and calculates    temperature difference ΔT, which is the temperature difference    between the upstream side end and the downstream side end of the    irradiation area on the wafer in the scanning direction. In    addition, main controller 20 uses the information for calculating    water temperature distribution within the irradiation area on the    wafer (such as computation formula or table data) stored in memory    21, in order to obtain the water temperature distribution by    computation, based on the calculated temperature difference ΔT and    the flow amount of the water flowing under lens 42.-   b. In addition, main controller 20 uses the information stored in    memory 21 (such as computation formula or table data), and    calculates the temperature change coefficient that corresponds to    the change in best focus position, for example, at points on both    sides within the irradiation area in the scanning direction, based    on the water distribution obtained.-   c. In addition, main controller 20 uses the table data or    computation formula stored in memory 21, and calculates the pressure    change coefficient that corresponds to the change in best focus    position, for example, at points on both sides within the    irradiation area in the scanning direction, based on the scanning    speed of wafer W and the water supply amount.-   d. In addition, main controller 20 substitutes the temperature    change coefficient and pressure change coefficient obtained    respectively in b. and c. above into a computation formula stored in    memory 21 for calculating the aberration previously described, such    as in the computation formula for calculating the best focus    position, and calculates the best focus position, for example, at    points on both sides within the irradiation area in the scanning    direction.-   e. In addition, main controller 20 calculates the shape of the image    plane (inclination of the image plane) of the projection optical    system based on the results calculated in d. above at this point,    and sets the target position (sets the detection offset) at each    detection point (irradiation pint of the imaging beams) of the focal    position detection system based on the calculation results, and    based on the target values, main controller 20 performs focus    control and leveling control of wafer W. That is, main controller 20    controls the movement of Z tilt stage 30 and wafer holder 70 so that    the surface of wafer W substantially coincides with the image plane.-   f. Main controller 20 repeats the processing a. to e. described    above during scanning exposure at a predetermined interval. As a    result, each point on wafer W is driven along the image plane of    projection optical system PL, and defocus, which is generated during    exposure caused by the water temperature change of the water between    lens 42 and wafer W or the pressure change due to the water flow,    can be effectively suppressed.

When scanning exposure of the first shot on wafer W is completed in thismanner, stage control unit 19 steps wafer stage WST via wafer stagedrive section 24, for example, in the X-axis direction in response tothe instructions from main controller 20, to the acceleration startingpoint for exposing the second shot (the shot area serving as a seconddivided area) on wafer W. And on the stepping operation (movementoperation between divided areas) of wafer stage WST between shots aswell, between the exposure of the first shot and the exposure of thesecond shot, main controller 20 performs the open/close operation ofeach valve in a similar manner as in the case when wafer stage WST movesfor exposure from the water supply position to the acceleration startingposition. With this operation, even when during the stepping operationbetween shots, the water is supplied to the space below lens 42 from therear side to the front side of projection unit PU in the movementdirection of wafer stage WST, and its amount is maintained at a constantamount at all times.

Next, scanning exposure is performed for the second shot on wafer W inthe manner similar to the description above under the control of maincontroller 20. In the embodiment, because the so-called alternatescanning method is employed, when the second shot is exposed, thescanning direction (moving direction) of reticle stage RST and waferstage WST is the opposite of the first shot. The processing of maincontroller 20 and stage control unit 19 during the scanning exposure ofthe second shot is basically the same as the processing previouslydescribed. In this case as well, main controller 20 adjusts the degreeof opening (including a fully closed state and a fully opened state) ofeach valve constituting valve groups 62 a and 62 b, so that in themoving direction of wafer W, which is opposite to the exposure of thefirst shot, a water flow is created under lens 42 that moves from therear side of projection unit PU to the front side. FIG. 10B shows asimplified view of the vicinity of liquid supply/drainage unit 32 atsuch a point, and it shows that wafer W moves in the −Y direction whenscanning exposure of the second shot is performed and that the waterflows between lens 42 and wafer W in the same direction as wafer W (the−Y direction).

In this manner, scanning exposure of the shot area on wafer W and thestepping operation are repeatedly performed, and the circuit pattern ofreticle R is sequentially transferred onto the shot areas of wafer Wserving as a plurality of divided areas.

FIG. 8B shows an example of a positional relationship between waferstage WST and projection unit PU during while exposure based on thestep-and-scan method is being performed for wafer W.

When scanning exposure for the plurality of shot areas on wafer W iscompleted in the manner described above, main controller 20 givesinstructions to stage control unit 19, and moves wafer stage WST to apredetermined water drainage position. FIG. 8C shows the state wherewafer stage WST has been moved to the water drainage position. In FIG.8C, reference letter PU indicates the position of the tip of barrel 40of projection unit PU. In this case, the water drainage position is setto a position where the tip of barrel 40 is positioned directly aboveauxiliary plate 22 c.

Next, main controller 20 fully closes all the valves in valve group 62a, while fully opening all the valves in valve group 62 b. At the sametime, main controller 20 lowers all the full recovery nozzles 56 viadrive mechanism 63 so that the tip of full recovery nozzles 56 comesinto contact with auxiliary plate 22 b, and then opens valve 62 c.

By such an operation, the water below lens 42 is completely collected byliquid recovery unit 74 after a predetermined period of time.

Then, wafer stage WST moves to the wafer exchange position, and waferexchange is performed.

As is obvious from the description so far, in exposure apparatus 100 inthe embodiment, a supply mechanism that supplies the liquid (water) tothe space between projection optical system PL and wafer W on waferstage WST, is made up of parts such as liquid supply unit 72, supplypipe line 64 connecting to liquid supply unit 72, the plurality ofsupply pipes 58 respectively connected to supply pipe line 64 via valves62 a, each supply nozzle 36 of liquid supply/drainage unit 32respectively connecting to the plurality of supply pipes 58, the widenednozzle section communicating with each supply nozzle 36, and the like.

In addition, in exposure apparatus 100, a recovery mechanism, thatcollects the liquid (water), is made up of parts such as liquid recoveryunit 74, recovery pipe line 66 connecting to liquid recovery unit 74,the plurality of recovery pipes 52 respectively connected to recoverypipe line 66 via valves 62 b, the tapered nozzle section communicatingwith the tip of each recovery pipe 52, and the like.

In addition, in exposure apparatus 100, an auxiliary recovery mechanismis formed by parts such as vacuum exhaust unit 76, vacuum piping system69 connecting to vacuum exhaust unit 76, auxiliary recovery pipes 60 ₁to 60 ₄ connecting to vacuum piping system 69 via valves 62 e, slits 32h ₁ to 32 h ₄ of liquid supply/drainage unit 32 connecting to each ofthe auxiliary recovery pipes, respectively, and the like. This auxiliaryrecovery mechanism can remove (recover) the liquid on wafer W that theliquid recovery mechanism could not recover. In the embodiment, theauxiliary recovery mechanism removes (recovers) the remaining liquid onwafer W by suction; however, it also may be removed by blowing dry airto dry up the liquid, or blown and scattered.

In addition, in exposure apparatus 100, a supply mechanism, thatsuppresses the environmental change in the periphery of the water(liquid), which occurs due to suction by vacuum exhaust unit 76, is madeup of parts such as air conditioning mechanism 86 and gas supply nozzles85 ₃ and 85 ₄, and the like.

In addition, in exposure apparatus 100, a drive system, that drivesreticle stage RST and wafer stage WST synchronously in the scanningdirection with respect to illumination light IL in order to transfer thereticle pattern onto wafer W in a scanning exposure method, isconstituted by reticle stage drive section 11, wafer stage drive section24, and stage control unit 19.

In addition, ring-shaped side wall 32 c is provided so as to partitionopening 32 a (lens 42 on the image plane side of projection opticalsystem PL is disposed in the center of opening 32 a) formed in thecenter of liquid supply/drainage unit 32, and ring-shaped depressedsection 32 b is also provided on the outer side of ring-shaped side wall32 c whose ceiling height is set higher than other sections, therefore,even when the water (liquid) is supplied into liquid supply/drainageunit 32, a void space remains within the inside of ring-shaped depressedsection 32 b. In this manner, in exposure apparatus 100, an bubblerecovery mechanism is made up of parts such as ring-shaped side wall 32c, ring-shaped side wall 32 e, exhaust pipes 54 connecting to the upperspace of ring-shaped depressed section 32 b formed by ring-shaped sidewall 32 c and ring-shaped side wall 32 e, and the like. Furthermore, inthis case, because ring-shaped side wall 32 c and ring-shaped depressedsection 32 b are both formed surrounding projection unit PU covering theentire circumference, it is substantially equivalent to having a largenumber of bubble recovery mechanisms provided covering all directions.

In addition, in exposure apparatus 100, an adjustment unit is configuredto adjust the exposure conditions, or more specifically, offset of thefocal position detection system (90 a, 90 b), conditions related tofocus leveling control of wafer W (imaging conditions), and the like,based on the actual measurement values (measured by temperature sensors38A and 38B) of temperature information on the water between projectionoptical system PL (to be more precise, lens 42) and wafer W and pressureinformation on the water between projection optical system PL (to bemore precise, lens 42) and wafer W, the unit being constituted by maincontroller 20. Furthermore, in exposure apparatus 100, a prediction unitis configured to predict the temperature change of the water that occurswhen the water passes through the irradiation area of illumination lightIL on the wafer, based on detection results of the two temperaturesensors 38A and 38B disposed on one end and the other end in thescanning direction, respectively, the unit also being constituted bymain controller 20.

The number of temperature sensors does not necessarily have to be two,and if the temperature change can be obtained by one sensor, only onemay be necessary. Or, in order to obtain a more detailed temperaturedistribution, the exposure apparatus may comprise three or moretemperature sensors.

As is described in detail, according to exposure apparatus 100 in theembodiment, when the reticle pattern is transferred onto each shot areaon wafer W based on the scanning exposure method, the supply operationof supplying the water to the space between projection unit PU(projection optical system PL) and wafer W on wafer stage WST and itsrecovery operation are performed in parallel, by the supply mechanismand the recovery mechanism described above. That is, exposure(transferring the reticle pattern onto the wafer) is performed in astate where a predetermined amount of water (the water is exchanged atall times) is always filled (held) between lens 42, which constitutesprojection optical system PL at its tip, and wafer W mounted on waferstage WST. As a consequence, the immersion method is applied and thewavelength of illumination light IL on the surface of wafer W can beshortened to 1/n of the wavelength in the atmosphere (n is therefractive index of the water, which is 1.4), which improves theresolution of the projection optical system. In addition, because thewater supplied is exchanged at all times, foreign matters found on waferW can be removed by the flow of water.

In addition, the depth of focus of projection optical system PL isenlarged around n times when compared with that of the atmosphere;therefore, it is advantageous when focus leveling operation of wafer Wis performed using the focal position detection system (90 a, 90 b),because it makes it more difficult for defocus to occur. And, in thecase when the depth of focus has to be secured only around the samelevel as in the case of the air, the numerical aperture (NA) ofprojection optical system PL can be increased, which also improves theresolution.

In addition, when bubbles are found in the water (liquid) supplied fromthe supply mechanism, or when bubbles are generated just after the waterhas been supplied, such bubbles are collected at the upstream side ofthe flow with respect to projection unit PU (projection optical systemPL), by the bubble recovery mechanism. That is, the bubbles in the waterare collected by the bubble recovery mechanism, without reaching thespace below lens 42. Therefore, such an operation can prevent thetransmittance of illumination light IL from partially decreasing or theprojected image of the pattern from degrading due to the bubbles thatenter the space between lens 42 and wafer W.

In addition, as is obvious from FIGS. 10A and 10B, the bubble recoveryposition of the bubble recovery mechanism used for collecting bubbles isswitched, in accordance with the moving direction of wafer W (forexample, the moving direction in FIGS. 10A and 10B is the scanningdirection). Therefore, regardless of the direction that wafer W movesin, the bubbles can be kept from entering the space between lens 42 andwafer W during such movement.

In addition, when the plurality of shot areas on wafer W aresequentially being exposed, for example, in the case a situation occurswhere the water cannot be completely collected by the recovery mechanismreferred to above, such as when the water leaks outside liquidsupply/drainage unit 32, then the water that could not be collected, orin other words, the water that has leaked out, is removed (recovered)from wafer W by the auxiliary recovery mechanism described above. Withthis operation, the water does not remain on wafer W; therefore, variousinconveniences that occur due to the remaining (residual) water can beavoided. That is, measurement errors of wafer interferometer 18, whichmeasures the position of wafer stage WST, can be effectively suppressedby suppressing the occurrence of temperature distribution in theatmosphere or by suppressing the occurrence of a refractive index changein the atmosphere, caused by the heat of vaporization when the remainingwater evaporates. Furthermore, such an operation can prevent the waterremaining on the wafer from moving to the back of the wafer, so that thesituation where the wafer sticks to the carrier arm and becomesdifficult to separate from the carrier arm can be avoided.

In addition, exposure apparatus 100 comprises peripheral wall 32 f(projected section 32 g), which surrounds at least the periphery of lens42 serving as an optical element of projection optical system PL closestto the wafer and also creates a predetermined clearance with respect tothe surface of wafer W on wafer stage WST, and the clearance is set to asmall value of around Δh=1 to 2 mm. Therefore, the contact area betweenthe water within peripheral wall 32 f and the outside air is setextremely small, and by the surface tension of the water the liquid iskept from leaking outside peripheral wall 32 f via the clearance.Therefore, it becomes possible, for example, to recover the liquid(water) used in the immersion method without fail after the completionof exposure.

In addition, according to exposure apparatus 100 in the embodiment, evenwhen wafer stage WST moves to a position where projection unit PU (theprojection area of projection optical system PL) is away from wafer W ina state where the water is held between projection optical system PL(lens 42) and wafer W, such as when a shot area in the periphery onwafer W is exposed, or when the wafer on wafer stage WST is exchangedafter the exposure has been completed, the water can be kept fromflowing outside by holding the water between the projection opticalsystem and auxiliary plates (any of the plates from 22 a to 22 d). Suchan arrangement can prevent various inconveniences caused by the outflowof water from occurring. Furthermore, because the gap between auxiliaryplates 22 a to 22 d and wafer W is set to 3 mm and under, the surfacetension of the water prevents the water from flowing into the gapbetween wafer W and the auxiliary plate in a case, such as when waferstage WST moves from a state where wafer W is under projection unit PU(projection optical system PL) to a position where wafer W is away fromprojection unit PU. The inventors have confirmed that leakage hardlyoccurs due to the surface tension of the water even when there is asurface difference of around 1 mm between the surface of the wafer andthe surface of the auxiliary plate.

In addition, for example, when exposure begins after wafer W has beenexchanged, because the water is held between projection unit PU (lens 42of projection optical system PL) and the auxiliary plate prior to thebeginning of exposure, exposure can begin without waiting for the waterto be supplied, which consequently improves the throughput.

In addition, because the water supply into liquid supply/drainage unit32 begins on auxiliary plate 22 a before the exposure begins, the riskof the resist being partly removed by water pressure or the like as isoften the case when starting the water supply on wafer W can be avoided.

In addition, because air conditioning mechanism 86 (including gas supplynozzles) air conditions the periphery of liquid supply/drainage unit 32where the water is held, turbulence of the gas flow in the atmosphere(such as the air within the chamber where the main body of the exposureapparatus is housed) around the water held inside liquid supply/drainageunit 32 can be prevented when the water is recovered by the recoverymechanism or by the auxiliary recovery mechanism, which in turn preventsmeasurement errors of wafer interferometer 18 that may occur due to theturbulence of the gas flow (including temperature fluctuation of thegas, refractive index change, and the like), and allows the position ofwafer stage WST to be measured with good accuracy.

Accordingly, with exposure apparatus 100 in the embodiment, due to thevarious kind of effects as is described above, the pattern of reticle Rcan be transferred onto each of the plurality of shot areas on wafer Wwith an extremely good accuracy. In addition, exposure can be performedwith a wider depth of focus when compared with that of the air.

The arrangement of each section described in the above first embodimentis a mere example, and it is a matter of course that the presentinvention is not limited to this. For example, in the embodiment above,while wafer stage WST is moving, main controller 20 adjusts the degreeof opening (including a fully closed state and a fully opened state) ofeach valve constituting valve groups 62 a and 62 b so that a water flowis created under lens 42 that moves from the rear side of projectionunit PU to the front side in the moving direction of wafer stage WST. Onthe contrary, while wafer stage WST is moving, main controller 20 mayadjust the degree of opening (including a fully closed state and a fullyopened state) of each valve constituting valve groups 62 a and 62 b sothat a water flow is created under lens 42 that moves from the frontside of projection unit PU to the rear side in the moving direction ofwafer stage WST. In such a case, the auxiliary recovery mechanismreferred to earlier is to recover the remaining liquid on the front sideof projection unit PU (projection optical system PL) in the movingdirection of wafer W. That is, the remaining liquid is recovered viaslit 32 h _(i) located on the front side in the moving direction of thewafer and auxiliary recovery pipe 60 _(i) (i=any of 1 to 4)communicating with the slit.

In addition, in the first embodiment described above, an auxiliaryrecovery mechanism is constituted by parts such as slits 32 h ₁ to 32 h₄ formed in a part of liquid supply/drainage unit 32, auxiliary recoverypipes 60 ₁ to 60 ₄ communicating with slits 32 h ₁ to 32 h ₄,respectively, vacuum exhaust unit 76, and the like, however, forexample, air conditioning mechanism 86 may include a suction mechanismthat suctions liquid (liquid and gas). That is, air conditioningmechanism 86 may incorporate a vacuum pump, and a suction nozzleconnecting to the vacuum pump may be disposed in the vicinity of eachgas supply nozzle previously described. By employing such anarrangement, the vacuum pump serving as a suction mechanism may alsoperform the function of recovering the water that the recovery mechanismpreviously described could not recover (the water that leaks outsideliquid supply/drainage unit 32). In this case, slits 32 h ₁ to 32 h ₄ donot have to be formed in liquid supply/drainage unit 32, and inaccordance with the position where the suction nozzle is disposed, thesuction nozzle may be able to cope with water leakage in a slightlylarger range. In addition, in the embodiment described above, the watersupply and recovery are performed while wafer W is being exposed. In thecase, however, the water can be held by surface tension, water supplyand recovery operations do not have to be performed during exposure.

In addition, air conditioning mechanism 86 may remove the remainingwater from wafer W that could not be recovered by the recovery mechanismoutside peripheral wall 32 g by providing dry air or hot air so as todry the remaining water.

In the embodiment above, fiducial mark plate FM is disposed on a part ofthe auxiliary plate, however, instead of this arrangement, or along withfiducial mark plate FM, a reference reflecting plate used forcalibration of the focal position detection system (90 a, 90 b) may bedisposed on a part of the auxiliary plate. Or, the reference reflectingplate and fiducial mark plate FM may be combined in one plate. Inaddition, the auxiliary plate is provided covering the entire peripheryof wafer W, however, it can be also disposed partially at requiredplaces, or it can be disposed spaced apart at a predetermined interval.

In addition, in the embodiment above, besides the stepping operationbetween shots and scanning exposure when wafer stage WST is standingstill, main controller 20 may cease both the water (liquid) supplyoperation by the supply mechanism previously described and the waterrecovery operation by the recovery mechanism also previously described.Even in such a case, the water inside liquid supply/drainage unit 32 isheld due to the action of negative pressure described earlier and thesurface tension of the water. Because the need to exchange the water islower in the case wafer stage WST is stationary when compared with thecase of stepping operation between shots and scanning exposure, theamount of liquid to be used can be reduced compared with the case whenboth the liquid supply operation by the supply mechanism and the liquidrecovery operation by the recovery mechanism are performed in parallelat all times (not only when wafer stage WST is moving, but also when itis still). However, by continuing the water supply and drainage whilewafer stage WST is stationary, it may free the lower surface of lens 42from contamination.

In addition, in the embodiment above, the case has been described whereas a premise, the water supply position and the water drainage positionshown in FIGS. 8A and 8C, respectively, do not have any relation withthe wafer exchange position (wafer unload position and load position).The present invention, however, is not limited to this, and for example,the water supply position may serve as the wafer loading position andthe water drainage position as the unload position. Such an arrangementmay be realized by adjusting the relation between the area of the tip ofprojection unit PU and the area of wafer stage WST (to be more precise,the auxiliary plate) so that projection PU does not get in the way ofwafer transportation. In this case, the water supply and the waterdrainage may be continued or sustained at the unload position and loadposition of the wafer. In such a case, the load position and the unloadposition of the wafer may be set at the same position (referred to as awaiting position) where fiducial mark plate FM is to be positioneddirectly below projection unit PU, and the area of wafer stage WST (orto be more precise, the auxiliary plate) may be set so that the tip ofprojection unit PU is located above any one of auxiliary plates 22 a to22 d during wafer alignment.

In such a case, because it becomes possible to hold the water at alltimes under lens 42, the water supply and water drainage previouslydescribed may be continued during a period other than the exposureoperation based on the step-and-scan method. In this case, once thewater is supplied under lens 42, exposure of a plurality of wafers canbe continuously performed without draining all the water under lens 42.

In addition, in the embodiment above, liquid supply/drainage unit 32comprising peripheral wall 32 f is used in order to hold the water underlens 42 of projection unit PU, however, the present invention is notlimited to this. That is, for example, liquid supply/drainage unit 32does not have to be used. Even in such a case, because the distance(working distance) between lens 42 of projection optical system PL andwafer W is around 3 mm, the water is held by surface tension betweenlens 42 and wafer W. In addition, in this case, for example, a mechanismsimilar to the liquid supply mechanism and liquid recovery mechanism,disclosed in the pamphlet of International Publication Number WO99/49504or the like previously described, may be provided. In such anarrangement, due to the auxiliary plates described earlier, even whenprojection unit PU deviates from above wafer W such as when the waferedge section is exposed, the water can be kept from leaking from underlens 42 unlike patent document 1. In this case, while wafer stage WST isstanding still, the water supply and water drainage may also be stopped.In this case, due to the immersion method, exposure with high resolution(or exposure with a wider depth of focus compared with the case in theatmosphere) can be performed. Accordingly, the pattern can betransferred onto the wafer with good accuracy.

In the case, however, as in the embodiment above, a unit like liquidsupply/drainage unit 32 whose nozzle section and the enclosure(peripheral wall 32 f) around lens are integrated is used, the exchangeoperation can be done all at once, which simplifies the maintenanceoperation.

In the embodiment above, the valves for supplying and draining the waterconnect directly to the nozzle section of liquid supply/drainage unit 32via piping, and as these piping, flexible tubes are preferably used.Furthermore, the tubes that connect to the valves and factory piping arepreferably separated mechanically from the main body of the exposureapparatus and projection unit PU via springs, so that the vibration doesnot spread. And, such an arrangement can prevent vibration and waterhammer that accompany the opening and closing of the valves fromtraveling and affecting the projection unit PU and the main body of theexposure apparatus, and becoming the cause of various errors.

In addition, in exposure apparatus 100 of the embodiment above, in thecase multiple exposure such as double exposure is performed, after thefirst pattern is transferred onto a plurality of divided areas (shotareas) on wafer W based on the step-and-scan method in a state where thespace between projection unit PU (lens 42 of projection optical systemPL) and wafer W is filled with the liquid, the second pattern may betransferred on the plurality of shot areas on wafer W with the waterbeing held between lens 42 and wafer W. In this case, as reticle stageRST, a stage that can hold two reticles based on the so-called doublereticle holder method is preferably used, such as the one disclosed in,for example, Japanese Patent Application Laid-open No. H02-166717. Withthis arrangement, because reticle alignment and wafer alignment do nothave to be performed between the first shot and the second shot, doubleexposure can be performed without any problems in a state where thespace between projection unit PU (lens 42 of projection optical systemPL) and wafer W is filled with the liquid between the exposure of thefirst pattern and the exposure of the second pattern. In this case,multiple exposure that uses the immersion method is applied, and ahighly precise exposure with high resolution and a substantiallyenlarged depth of focus can be performed. In this case, since the liquidis held between lens 42 and wafer W at the point where exposure beginson the second pattern, the exposure of the second pattern can startwithout waiting for the liquid to be supplied.

In the embodiment above, reticle alignment may be performed in a statewhere the space between projection unit PU (lens 42 of projectionoptical system PL) and fiducial mark plate FM is filled with the water.

In addition, in the embodiment above, main controller 20 serving as anadjustment unit obtains the aberration within the irradiation area ofillumination light IL, such as the temperature change coefficient thatcorresponds to the change in best focus position, based on themeasurement results of temperature sensors 38A and 38B (the actualmeasurement values of temperature information on the water betweenprojection optical system PL (lens 42) and wafer W), however, maincontroller 20 may obtain the temperature change coefficient based onprediction values of temperature information on the water betweenprojection optical system PL (lens 42) and wafer W instead. In thiscase, information on the transmittance of reticle R and the reflectanceof wafer W that have been measured is stored in advance in memory 21,and when exposure is performed, main controller 20 obtains the thermalabsorption amount of the wafer by performing a predetermined calculationusing the output of integrator sensor 14, the transmittance of reticle Rand the reflectance of wafer W, and then predicts the temperature rise(temperature distribution) of the water in the irradiation area, basedon the obtained thermal absorption amount and information on the waterflow (flow speed and flow rate) under lens 42 due to water supply, waterdrainage, and scanning operation. Then, main controller 20 can obtainthe temperature change coefficient based on the prediction results, in amanner similar to the one described in the embodiment above. As a matterof course, when obtaining the temperature change coefficient, maincontroller 20 may use the actual measurement values of temperatureinformation on the water between projection optical system PL (lens 42)and wafer W and the predicted values based on the output of integratedsensor 14 and the like described above at the same time.

In addition, in the embodiment above, main controller 20 obtains thetemperature change coefficient and the pressure change coefficient, andthen obtains the best focus position within the irradiation area basedon a formula or the like that includes both the coefficients asparameters. The present invention, however, is not limited to this, andmain controller 20 may obtain either one of the temperature changecoefficient and the pressure change coefficient, and then may obtain thebest focus position within the irradiation area by using the formulareferred to above but substituting zero as the remaining changecoefficient. In this case, main controller may obtain the best focusposition directly from a formula that does not include the temperaturechange coefficient and the pressure change coefficient as parameters,such as from the temperature distribution or the pressure distributionof the water within the irradiation area.

In addition, in the embodiment above, the case has been described whereas the exposure condition, main controller 20 adjusts the offset of thefocal position detection system and performs the focus leveling of waferW, based on the best focus positions on both ends of the scanningdirection within the irradiation area obtained in the manner describedabove. The present invention, however, is not limited to this, and thepattern surface of reticle R may be adjusted or the inclination of theimage plane itself of projection optical system PL may be adjusted viaimage forming quality correction controller 81, as the exposurecondition, based on the obtained best focus positions on both ends ofthe scanning direction within the irradiation area. Then, when theinclination of the image plane cannot be totally corrected, maincontroller 20 may perform the offset adjustment of the focal positiondetection system and perform the focus leveling of wafer W described inthe embodiment above, based on the state of the image plane aftercorrection.

In addition, in the case when it is predicted that the temperaturechange (temperature distribution) of the water will affect themeasurement of the focal position detection system (90 a, 90 b), focusleveling control may be performed taking into consideration measurementerrors due to the temperature change (temperature distribution) of thewater, or the detection results of the focal position detection system(90 a, 90 b) may be corrected based on the output of temperature sensors38A and 38B, and focus leveling control may be performed, based on thecorrected detection results.

In addition, furthermore in the embodiment above, the pressure change(pressure distribution) of the water is obtained in advance bysimulation or by experiment, and the movement of Z tilt stage 30 iscontrolled based on the results, however, the movement of Z tilt stage30 may also be controlled, for example, based on the measurement resultsof the pressure of the water, which may be measured by a pressure sensorattached to the liquid supply/drainage unit.

In addition, the embodiment above focuses on the pressure change of thewater due to the water flow. However, the movement of wafer stage WSTmay be controlled and the imaging operation may be corrected by takinginto consideration the water pressure in the case no water flow exists(in the case the liquid supply/drainage unit does not perform the watersupply/recovery).

In addition, the embodiment above describes the case where focusleveling control error due to the temperature change or pressure changedoes not occur, however, in the case changes occur in the various typesof aberrations (such as spherical aberration, astigmatism, distortion,and magnification) of the image of the pattern projected within theirradiation area on wafer W due to the temperature change or pressurechange as is described above, such changes may be corrected byoperations such as adjusting projection optical system PL, adjusting thewavelength of illumination light IL, and moving reticle R, based on thetemperature change (temperature information) and the pressure change(pressure information) of the water.

Depending on the type of resist on the wafer, resist substances maydissolve into the water and have an adverse effect on the image forming.In such a case, it is necessary to reduce the influence that thedissolved material of the resist, which seeps out when the previous shotarea is exposed, has on the image forming of the next shot. Thefollowing second embodiment has been made from such an aspect.

Second Embodiment

A second embodiment of the present invention is described below,referring to FIGS. 11A to 11F. For parts that have the same or similararrangement as the first embodiment previously described, the samereference numerals will be used, and the description thereabout will bebrief, or entirely omitted. The arrangement of an exposure apparatus inthe second embodiment is similar to that of the first embodiment, otherthan the supply/drainage method of the water via liquid supply/drainageunit 32 by main controller 20. Accordingly, from the viewpoint ofavoiding any repetition, the following description will be made focusingon the points different from the first embodiment.

In the exposure apparatus of the second embodiment, when operationsother than the exposure operation based on the step-and-scan method isperformed, more specifically, when wafer exchange and predeterminedpreparatory operations (reticle alignment, baseline measurement of thealignment detection system, and wafer alignment) are performed, thewafer exchange and the predetermined preparatory operations areperformed in the same manner as in the first embodiment except for thepoint that the supply and recovery (drainage) of the water on wafer Ware not performed at all during such operations.

Accordingly, in the description below, operations when transferring areticle pattern onto a plurality of shot areas on a wafer based on thestep-and-scan method will be described, especially the operation duringscanning exposure of shot areas and the stepping operation in betweenshots.

As a premise, liquid supply unit 72, liquid recovery unit 74, and vacuumexhaust unit 76 shown in FIG. 6 are to be operating, and the valves invalve groups 62 a and 62 b fully open, while valve 62 c is fully closed,and the valves in valve groups 62 d and 62 e are opened to apredetermined degree.

FIGS. 11A to 11F show a water supply/drainage operation flow while waferstage WST is scanned to expose a shot area of an exposure apparatusrelated to the second embodiment. The water supply/drainage method inthe second embodiment will now be described below, referring to thedrawings.

FIG. 11A shows a state where a shot area SA subject to exposure nears aprojection area (an irradiation area on wafer W where illumination lightIL is irradiated via reticle R and projection optical system PL) IA ofprojection unit PU by stage control unit 19 driving wafer stage WST (atthis point, reticle stage RST is also driven in the opposite directionof wafer stage WST at a speed corresponding to the projectionmagnification) under the control of main controller 20. While waferstage WST is moving, main controller 20 adjusts the degree of opening ofeach valve in valve group 62 a of the water supply so that the water issupplied on wafer W via supply pipes 58 on the rear side of projectionunit PU with respect to the moving direction (scanning direction). Thegray area (WTR) in FIG. 11A shows the area on the surface of wafer Wwhich is covered with water. In this state, each valve of valve group 62b of the water drainage (water recovery) is set at a fully closed stateas is previously described.

Then, wafer stage WST moves in the scanning direction while the watersupply continues, and the area covered with water (WTR) spreads alongwith the movement of wafer stage WST (wafer W) as is shown in FIG. 11B.The state shown in FIG. 11B is the state immediately before shot area SAsubject to exposure is about to be exposed.

Then, when shot area SA reaches the exposure area, exposure of shot areaSA is performed in the same manner as is previously described.

During exposure, as is shown in FIG. 11C, part of shot area SP thatpasses through projection area IA is in a state covered with water atall times.

From the point shown in FIG. 11C (or from before such a point), maincontroller 20 adjusts the degree of opening of each valve in valve group62 b of the water drainage so as to collect the water covering the partwhere exposure has been completed. In this case, the valves in valvegroup 62 b, which are provided at a position substantially symmetricalto the valves in valve group 62 a that are opened for water supply withrespect to projection unit PU, are opened.

And, as is shown in FIG. 11D, stage control unit 19 drives wafer stageWST while exposure of shot area SA that passes through projection areaIA is being performed and the water that covers the part where exposurehas been completed is collected. Then, as is shown in FIG. 11E, exposureof shot area SA is completed.

As soon as exposure is completed in the manner above, at the same timemain controller 20 completely closes each of the valves in valve group62 a used for water supply. Then, at the stage where water on wafer W iscompletely drained as is shown in FIG. 11F, main controller 20completely closes each of the valves of valve group 62 b.

In the manner described above, exposure operation to a shot area SA, andthe water supply/recovery operation, or in other words, the watersupply/drainage operation performed synchronously with the exposureoperation is completed.

Then, according to instructions given from main controller 20, stagecontrol unit 19 performs the stepping operation between shots in thesame manner as in the first embodiment. However, during the steppingoperation, none of the water is supplied on wafer W.

Then, for the next shot area, scanning exposure (transfer of the reticlepattern) and the water supply/drainage operation synchronous to theexposure operation are performed in the same manner as is describedabove. In this case, main controller 20 controls each section so thatthe moving direction of wafer W and the flow direction of the watersupplied on wafer W are in the opposite of the case described in FIGS.11A to 11E.

And, in the manner described above, the scanning exposure of the shotarea on wafer W and the stepping operation between shots are repeatedlyperformed, and the circuit pattern of reticle R is sequentiallytransferred onto the plurality of shot areas serving as divided areas onwafer W.

As is described above, according to the exposure apparatus in the secondembodiment, the water supply by the supply mechanism previouslydescribed to the inside of peripheral wall 32 f, which includes thespace between projection unit PU (lens 42 of projection optical systemPL) and wafer W on wafer stage WST) and the water recovery by therecovery mechanism are performed in sync with the exposure operation toeach shot area on wafer W. Therefore, when a pattern is transferred ontothe shot area on wafer W subject to exposure based on the step-and-scanmethod, while the shot area passes through irradiation area IA ofillumination light IL via projection optical system PL, a predeterminedamount of water (the water can be exchanged at all times) can be filledbetween lens 42 and wafer W, and by the immersion method, exposure withhigh resolution and a wider depth of focus can be performed whencompared with the case when exposure is processed in air. On the otherhand, besides the irradiation period while the shot area subject toexposure passes through irradiation area IA or the period including theirradiation period and a slight length of time after the irradiationperiod, wafer W can be in a state free of any water on its surface. Thatis, when the plurality of shot areas on wafer W is sequentially exposed,because the supply and the full recovery of the water between lens 42 ofprojection optical system PL and wafer W are repeatedly performed eachtime exposure of the shot area is performed, decrease in transmittanceof illumination light IL, adverse effect on the image forming, and thelike due to substances of the photosensitive agent (resist) on wafer Wdissolving into the water can be suppressed.

In addition, in the exposure apparatus in the second embodiment, thesupply mechanism has a plurality of supply nozzles 36 in the peripheryof irradiation area IA, and supply nozzle 36 used for water supplyswitches in accordance with the scanning direction (moving direction) ofwafer W. More specifically, each time a shot area is exposed, the wateris supplied by the supply mechanism from the rear side in the scanningdirection of wafer W, and corresponding to this operation, the water isfully recovered by the recovery mechanism on the front side in thescanning direction. Therefore, the immersion method is applied to eachexposure of the shot area, regardless of the scanning direction.

In addition, the water supplied to the inside of peripheral wall 32 ffrom the rear side in the scanning direction of wafer W by the supplymechanism previously described, is recovered by the recovery mechanismalso previously described on the front side of projection unit PU in thescanning direction. In this case, the water supplied flows along in thescanning direction of wafer W in between lens 42 and wafer W. Therefore,in the case foreign matters are found on wafer W, the water flow removessuch substances.

In addition, also in the second embodiment, bubbles found in the waterare collected by the bubble recovery mechanism previously described asin the first embodiment, at the rear side of projection unit PU in thescanning direction of the wafer. In this case, when the scanningdirection of wafer W is switched, then corresponding to such anoperation, the bubble recovery mechanism used for collecting the bubblesis also switched.

In addition, in the exposure apparatus in the second embodiment, whenthe pattern is transferred, the water supply by the supply mechanism isstopped at the point where the rear end of the shot area subject toexposure moves off irradiation area IA due to the movement of the waferstage in the scanning direction. Therefore, this effectively suppressesvibration caused by the drive of the valves and the water hammeraccompanying the drive from traveling to projection unit PU anddegrading the image forming quality of projection optical system PL.Furthermore, the amount of water supplied can be reduced as much aspossible, so as to reduce the time required for recovery.

In addition, in the exposure apparatus in the second embodiment, whenthe pattern has been transferred on a shot area subject to exposure, thewater is recovered by the recovery mechanism before the steppingoperation of wafer stage WST between shots performed prior to thepattern transfer of the next shot area begins. Therefore, this frees theexposure of the next shot area from adverse effects due to substances ofthe photosensitive agent (resist) of wafer W dissolving into the water.Furthermore, the water supply and recovery mechanism in the steppingdirection can be omitted.

In the second embodiment described above, the case has been describedwhere the supply mechanism begins the water supply when the front end ofthe shot area subject to exposure in the scanning direction reaches thesupply position (or immediately before) as is shown in FIG. 11A. Thepresent invention, however, is not limited to this, and the supplymechanism may begin the water supply at either point; after the steppingoperation of wafer stage WST between transferring the pattern onto theshot area subject to exposure and transferring the pattern onto thepreceding shot area has been completed, after wafer stage WST has begunits movement for exposure of the succeeding shot area, and before thefront end of the shot area subject to exposure in the scanning directionreaches the supply position. In this case, the supply mechanism suppliesthe water to the inside of peripheral wall 32 f, which includes thespace between projection unit PU (lens 42 of projection optical systemPL) and wafer W on wafer stage WST, from the rear side in the movingdirection (scanning direction) of wafer W, and fills the space betweenlens 42 and wafer W with the water upon the movement of wafer W. In thiscase, when shot area SA on wafer W subject to exposure moves to theposition under lens 42, the water is supplied on shot area SA withoutfail before shot area SA reaches the position under lens 42. That is,when wafer W is moved in the scanning direction, water is supplied tothe space between lens 42 and the surface of wafer W. Accordingly, byperforming exposure (transfer of the pattern of reticle R onto wafer W)of shot area SA, which serves as the area subject to exposure, theimmersion method previously described is applied, and exposure isperformed with high resolution and a wider depth of focus compared withthe case when exposure is processed in air.

In the second embodiment described above, as is shown in FIG. 12, forexample, on the lower end section of liquid supply/drainage unit 32, aplurality of partitions 87 a and 87 b extending in the scanningdirection may be provided, at positions on both sides in thenon-scanning direction of a plurality of supply nozzles 36 (supplynozzles that are within a range corresponding to projection area(irradiation area) IA of the pattern in the non-scanning direction)arranged spaced apart in the non-scanning direction. In this case,within each area partitioned by partitions 87 a and 87 b where supplynozzles 36 are each disposed, recovery pipes 52 are disposed with eachpipe corresponding to each of the supply nozzles 36. Then, maincontroller 20 may switch supply nozzle 36 used for water supply by thewater supply mechanism in accordance with the position of the shot areaon wafer W subject to exposure, and accordingly, recovery pipes 52 usedfor water recovery may also be switched. In this case, supply nozzles 36and recovery pipes 52 may be switched by the selective open/closeoperation of each valve in valve groups 62 a and 62 b.

Normally, a plurality of so-called chipped shots that are partly chippedis located in the periphery on wafer W, and in such chipped shots, thereare some shots like shot area SA_(n) in FIG. 12 whose size in thenon-scanning direction is smaller than that of other shot areas (shotareas located in the inner section on wafer W). The position of chippedshot SA_(n) on wafer W and the shape of the shot (including the size) isknown. Therefore, when exposing SA_(n), main controller 20 can performthe open/close control of each valve in valve groups 62 a and 62 b sothat the water is supplied from, for example, supply nozzle 36Qindicated by a ● in FIG. 12, and recovered by recovery pipe 52Q alsoindicated by a ●. And, when such a control is performed, watersupply/drainage is not performed in the chipped part in shot areaSA_(n). Accordingly, by completely draining the water from the area onwafer W other than the shot area subject to exposure before theexposure, it can prevent the water from leaking as much as possible whenexposing the chipped area, even in the case where the size of auxiliaryplates 22 a to 22 d of wafer holder 70 cannot be increased.

In this case, it is a matter of course that supply nozzle 36 used forwater supply and recovery pipe 52 are switched, in accordance with thescanning direction of wafer W.

In addition, main controller 20 may switch supply nozzle 36 used forwater supply by the water supply mechanism in accordance with the sizeof the shot area in the non-scanning direction instead of the positionof the shot area subject to exposure on the wafer, as well asaccordingly switch recovery pipe 52 used for collecting the water. Insuch a case, even when transferring a pattern of a different size ontothe same or a different wafer, exposure can be performed smoothly.

In addition, in the second embodiment described above, the case has beendescribed where the water supply is stopped when exposure of the shotarea on wafer W has been completed (refer to FIG. 11E). The presentinvention, however, is not limited to this, and it is possible to employan exposure sequence such as the one shown in FIGS. 13A to 13F.

In this case, the processing in FIGS. 13A to 13C is the same as in FIGS.11A to 11C previously described. However, at the point just before therear end of shot area SA subject to exposure in the scanning directionmoves off irradiation area IA, or to be more specific, at the pointwhere the rear end of shot area SA reaches the supply position (watersupply position (the position of supply pipe 58)) shown in FIG. 13D,main controller 20 completely closes valve group 62 a, and cuts off allwater supply until the exposure operation is over. This reduces the timerequired to drain the water completely, because the range to which thewater is supplied is smaller (refer to FIGS. 13E and 13F) when comparedwith the case described referring to FIGS. 11A to 11F. Accordingly, inthe case vibration generated on water supply/drainage only has a smallinfluence on exposure accuracy, the throughput can be effectivelyimproved. In this case, again, the water is collected by the recoverymechanism, after the pattern has been transferred onto shot area SA andbefore the stepping operation of wafer stage WST between shots prior tothe pattern transfer onto the next shot area begins (refer to FIG. 13F).

As the liquid supply/drainage unit, its arrangement is not limited onlyto the ones described in the embodiments above, and various types ofarrangement can be employed.

For example, as in a liquid supply/drainage unit 32′ shown in FIG. 14A,the unit may be structured without having the bubble recovery mechanismand the full recovery nozzle provided, and comprise only a widenednozzle section, supply nozzles 36, and supply pipes 58 that constitutethe supply mechanism for supplying the water, a tapered nozzle sectionand recovery pipes 52 that constitute the recovery mechanism forcollecting the water, and slits 32 h ₃ and 32 h ₄ that constitute theauxiliary recovery mechanism, and the like. In this case, with lens 42as the center, the tapered nozzle section and recovery pipes 52 areprovided in the periphery of lens 42, and the widened nozzle section,supply nozzles 36, and supply pipes 58 are disposed on the outer side ofthe tapered nozzle section and recovery pipes 52. In the case whenliquid supply/drainage unit 32′ shown in FIG. 14A is employed, when, forexample, exposure is performed scanning the wafer from left to right,the water is supplied from supply pipes 58 on the left hand side viasupply nozzles 36 and the widened nozzle section, and a part of thewater supplied is drained and bubbles in the supplied water areexhausted by the tapered nozzle section and recovery pipes 52 on theleft side of lens 42, which suppresses the bubbles from passing underlens 42. Meanwhile, the tapered nozzle section and recovery pipes 52 onthe right side of lens 42 recover the water flowing below lens 42.

In this case, the tapered nozzle section, recovery pipes, widened nozzlesection, supply nozzles 36, supply pipes 58, and the like describedabove do not necessarily have to be provided covering the entireperiphery of lens 42, and for example, each one of them may be providedrespectively on both ends in the scanning direction. Regarding thispoint, the same can be said for liquid supply/drainage unit 32previously described.

In addition, in each of the embodiments described above, the watersupply and drainage by the liquid supply/drainage unit is performedusing different nozzles. The present invention, however, is not limitedto this, and for example, the water supply and drainage may be performedvia water supply/drainage nozzles 52′ as in a liquid supply/drainageunit 32″ shown in FIG. 14B. In this case, when wafer stage WST isscanned, the water may be supplied from a water supply/drainage nozzlelocated in the rear side in the scanning direction and collected by awater supply/drainage nozzle located in the front side in the scanningdirection. And, in this case, when bubbles are found in the water, theygather in the vicinity of the ceiling inside liquid supply/drainage unit32″ in the front side of lens 42 in the scanning direction, and when thescanning direction is reversed and the nozzles used for water supply anddrainage are switched, the bubbles are exhausted from the watersupply/drainage nozzle on the drainage side.

Furthermore, in the exposure apparatus described in each of theembodiments above, in lens 42 located closest to wafer W among thelenses that constitutes projection optical system PL, for example, as isshown in FIG. 15, holes may be formed in the portion that is not usedfor exposure, and the liquid supply by the supply mechanism, or theliquid recovery or bubble recovery of bubbles in the liquid by therecovery mechanism may be performed via such holes. In the case shown inFIG. 15, the liquid is recovered through the holes formed in lens 42.When such an arrangement is employed, the space can be saved compared tothe case when the supply mechanism and recovery mechanism are botharranged completely exterior to the projection optical system.

In each of the embodiments above, the case has been described whereultra pure water (water) is used as the liquid. As a matter of course,however, the present invention is not limited to this, and as theliquid, a liquid that is chemically stable, having high transmittance toillumination light IL, and safe to use, such as a fluorine containinginert liquid may be used. As such as a fluorine-containing inert liquid,for example, Florinert (trade name; manufactured by 3M) can be used. Thefluorine-containing inert liquid is also excellent from the point ofcooling effect. In addition, as the liquid, a liquid which has hightransmittance to illumination light IL and a refractive index as high aspossible, and furthermore, a liquid which is stable against theprojection optical system and the photoresist coated on the surface ofthe wafer (for example, cederwood oil or the like) can also be used.

In addition, in the above embodiment, the liquid recovered may bereused, and in this case, a filter that removes impurities from thecollected water is desirably provided in the liquid recovery unit,recovery pipes, and the like.

In each of the embodiments above, the case has been described where theoptical element closest to the image plane of projection optical systemPL is lens 42, however, the optical element is not limited to a lens andit may be an optical plate (plane-parallel plate) for adjusting theoptical properties such as aberration (spherical aberration, coma, andthe like) of projection optical system PL, or it may simply be a coverplate. The surface of the optical element closest to the image plane ofprojection optical system PL (lens 42 in each of the embodiments above)may be contaminated by scattered particles generated from the resistwith the irradiation of illumination light IL or by coming into contactwith the liquid (water in each of the embodiments above) containingimpurities. Therefore, the optical element is fixed detachable(exchangeable) to the lowest section of barrel 40, and may beperiodically exchanged.

In such a case, however, when the optical element coming into contactwith the liquid is lens 42, the price of the exchanged component is highand the time required to complete the exchange operation is long, whichincreases the maintenance cost (running cost) as well as decreases thethroughput. Therefore, the optical element coming into contact with theliquid may be, for example, a plane-parallel plate since it has a morereasonable price than lens 42. In this case, even in the case whenmatters (such as organic matters containing silicon) that reduce thetransmittance of projection optical system PL, the illuminance ofillumination light IL on wafer W, the uniformity of the illuminancedistribution, or the like adhere to the plane-parallel plate at the timeof transportation, assembly, adjustment, or the like of the exposureapparatus, the plane-parallel plate can be exchanged just before theliquid is supplied, and the cost merit also increases due to the lessexpensive exchange cost when compared with the case when using a lensfor the optical element.

In addition, in each of the embodiments described above, the range wherethe liquid (water) flows can be set covering the entire projection area(irradiation area of illumination light IL) of the pattern area of thereticle, and its size may be optional, however, from the point such asflow speed, flow amount control, the range is preferably kept as smallas possible by setting it only slightly larger than the irradiationarea.

Furthermore, in each of the embodiments described above, auxiliaryplates 22 a to 22 d are provided in the periphery of the area wherewafer W is mounted on wafer holder 70, however, in the presentinvention, exposure apparatus that do not necessarily require anauxiliary plate or a flat plate that has a similar function on thesubstrate stage are available. In this case, however, it is preferableto further provide piping on the wafer stage for recovering the liquidso that the supplied liquid is not spilled from the substrate stage. Inaddition, in each of the embodiments above, the exposure apparatus isemployed whose space between projection optical system PL and wafer W islocally filled with liquid. However, in the present invention, there aresome parts that are applicable to an immersion exposure apparatus whosedetails are disclosed in, Japanese Patent Application Laid-open No.H06-124873, where a stage holding a substrate subject to exposure ismoved in a liquid bath, or to an immersion exposure apparatus whosedetails are disclosed in, Japanese Patent Application Laid-open No.H10-303114, where a wafer is held in a liquid pool of a predetermineddepth formed on a stage.

In each of the embodiments above, an ArF excimer laser is used as thelight source. The present invention, however, is not limited to this,and an ultraviolet light source such as a KrF excimer laser (wavelength248 nm) may also be used. In addition, for example, the ultravioletlight is not limited only to the laser beams emitted from each of thelight sources referred to above, and a harmonic wave (for example,having a wavelength of 193 nm) may also be used that is obtained byamplifying a single-wavelength laser beam in the infrared or visiblerange emitted by a DFB semiconductor laser or fiber laser, with a fiberamplifier doped with, for example, erbium (Er) (or both erbium andytterbium (Yb)), and by converting the wavelength into ultraviolet lightusing a nonlinear optical crystal.

In addition, projection optical system PL is not limited to a dioptricsystem, and a catadioptric system may also be used. Furthermore, theprojection magnification is not limited to magnification such as ¼ or ⅕,and the magnification may also be 1/10 or the like.

In each of the embodiments described above, the case has been describedwhere the present invention is applied to a scanning exposure apparatusbased on the step-and-scan method. It is a matter of course, however,that the present invention is not limited to this. More specifically,the present invention can also be suitably applied to a reductionprojection exposure apparatus based on a step-and-repeat method. In thiscase, besides the point that exposure is performed when both the mask(reticle) and the substrate (wafer) are substantially standing still,the exposure apparatus can basically employ a structure similar to theone described in the first embodiment and obtain the same effect. Inaddition, the present invention can also be applied to an exposureapparatus that comprises two wafer stages (twin stage type exposureapparatus).

The exposure apparatus in each of the embodiments described above can bemade, first of all, by incorporating the illumination optical systemmade up of a plurality of lenses and projection unit PU into the mainbody of the exposure apparatus, and attaching the liquid supply/drainageunit to projection unit PU. Then, along with the optical adjustmentoperation, parts such as the reticle stage and the wafer stage made upof multiple mechanical parts are also attached to the main body of theexposure apparatus and the wiring and piping connected. And then, totaladjustment (such as electrical adjustment and operation check) isperformed, which completes the making of the exposure apparatus. Theexposure apparatus is preferably built in a clean room where conditionssuch as the temperature and the degree of cleanliness are controlled.

In addition, in each of the embodiments described above, the case hasbeen described where the present invention is applied to exposureapparatus used for manufacturing semiconductor devices. The presentinvention, however, is not limited to this, and it can be widely appliedto an exposure apparatus for manufacturing liquid crystal displays whichtransfers a liquid crystal display deice pattern onto a square shapedglass plate, and to an exposure apparatus for manufacturing thin-filmmagnetic heads, imaging devices, micromachines, organic EL, DNA chips,or the like.

In addition, the present invention can also be suitably applied to anexposure apparatus that transfers a circuit pattern onto a glasssubstrate or a silicon wafer not only when producing microdevices suchas semiconductors, but also when producing a reticle or a mask used inexposure apparatus such as an optical exposure apparatus, an EUVexposure apparatus, an X-ray exposure apparatus, or an electron beamexposure apparatus. Normally, in the exposure apparatus that uses DUV(deep (far) ultraviolet) light or VUV (vacuum ultraviolet) light, ituses a transmittance type reticle, and as the reticle substrate,materials such as silica glass, fluorine-doped silica glass, fluorite,magnesium fluoride, or crystal are used.

<<Device Manufacturing Method>>

An embodiment is described below of a device manufacturing method in thecase where the exposure apparatus described above is used in alithographic process.

FIG. 16 shows a flow chart of an example when manufacturing a device(like an IC or an LSI as in a semiconductor chip, a liquid crystalpanel, a CCD, a thin magnetic head, a micromachine, or the like). As isshown in FIG. 16, in step 201 (design step), the function/performancedesign of a device (for example, designing a circuit for a semiconductordevice) is performed, and pattern design to implement such function isperformed. Then, in step 202 (mask manufacturing step), a mask on whichthe designed circuit pattern is formed is manufactured, whereas, in step203 (wafer manufacturing step), a wafer is manufactured using materialssuch as silicon.

Next, in step 204 (wafer processing step), the actual circuit or thelike is formed on the wafer by lithography or the like in a manner whichwill be described later on, using the mask and wafer prepared in steps201 to 203. Then, in step 205 (device assembly step), device assembly isperformed using the wafer processed in step 204. Step 205 includesprocesses such as the dicing process, the bonding process, and thepackaging process (chip encapsulation) when necessary.

Finally, in step 206 (inspection step), tests on operation, durability,and the like are performed on the devices made in step 205. After thesesteps, the devices are completed and shipped out.

FIG. 17 is a flow chart showing a detailed example of step 204 describedabove when manufacturing a semiconductor device. Referring to FIG. 17,in step 211 (oxidation step), the surface of the wafer is oxidized. Instep 212 (CVD step), an insulating film is formed on the wafer surface.In step 213 (electrode formation step), an electrode is formed on thewafer by vapor deposition. In step 214 (ion implantation step), ions areimplanted into the wafer. Steps 211 to 214 described above make up apre-process in each stage of wafer processing, and the necessaryprocessing is chosen and is executed at each stage.

When the above pre-process is completed in each stage of waferprocessing, a post-process is executed in the manner described below. Inthis post-process, first, in step 215 (resist formation step), the waferis coated with a photosensitive agent. Next, in step 216 (exposurestep), the circuit pattern on the mask is transferred onto the wafer bythe exposure apparatus and the exposure method described above. And, instep 217 (development step), the wafer that has been exposed isdeveloped. Then, in step 218 (etching step), an exposed member of anarea other than the area where the resist remains is removed by etching.Finally, in step 219 (resist removing step), when etching is completed,the resist that is no longer necessary is removed.

By repeatedly performing such pre-process and post-process, multiplecircuit patterns are formed on the wafer.

When the device manufacturing method described in this embodiment isused, because the exposure apparatus described in the embodiments aboveis used in the exposure process (step 216), the pattern of the reticlecan be transferred on the wafer with good accuracy. As a consequence,the productivity (including the yield) of highly integrated microdevicescan be improved.

While the above-described embodiments of the present invention are thepresently preferred embodiments thereof, those skilled in the art oflithography systems will readily recognize that numerous additions,modifications, and substitutions may be made to the above-describedembodiments without departing from the spirit and scope thereof. It isintended that all such modifications, additions, and substitutions fallwithin the scope of the present invention, which is best defined by theclaims appended below.

1. An exposure apparatus that illuminates a pattern with an energy beamand transfers the pattern onto a substrate via a projection opticalsystem, the exposure apparatus comprising: a substrate stage on whichthe substrate is mounted that moves within a two-dimensional planeholding the substrate; a supply system that supplies liquid to locallyfill a space between the projection optical system and the substrate onthe substrate stage with the liquid, so as to form an immersion areahaving a size smaller than a surface of the substrate that is subjectedto exposure; a recovery system that recovers the liquid; and a plateprovided in at least a part of the periphery of a mounted area of thesubstrate on the substrate stage, the plate having a surface arranged atsubstantially a same height as a surface of the substrate mounted onsaid substrate stage, wherein when an exposure operation is suspended,the liquid supplied by the supply system is held between the projectionoptical system and the surface of the plate.
 2. The exposure apparatusof claim 1, wherein a gap formed between the plate and the substrate isset to no more than 3 mm.
 3. The exposure apparatus of claim 1, theexposure apparatus further comprising: an interferometer that measures aposition of the substrate stage; and a conditioning system that performsenvironment conditioning in a periphery of the liquid between theprojection optical system and the substrate.
 4. The exposure apparatusof claim 1, wherein the liquid supply by the supply system begins on theplate.
 5. The exposure apparatus of claim 1, the exposure apparatusfurther comprising: a control system that stops both liquid supplyoperation by the supply system and liquid recovery operation by therecovery system when the substrate stage remains stationary.
 6. Theexposure apparatus of claim 1, wherein the supply system supplies liquidto the space between the projection optical system and the substrate onthe substrate stage from the front side in a moving direction of thesubstrate.
 7. The exposure apparatus of claim 1, wherein the supplysystem supplies liquid to the space between the projection opticalsystem and the substrate on the substrate stage from the rear side in amoving direction of the substrate.
 8. The exposure apparatus of claim 1,the exposure apparatus further comprising: a drive system that drivesthe substrate stage in a predetermined scanning direction with respectto the energy beam to transfer the pattern onto said substrate in ascanning exposure method.
 9. The exposure apparatus of claim 1, theexposure apparatus further comprising: at least one bubble recoverysystem that recovers bubbles in the liquid at the rear side of theprojection optical system in a moving direction of the substrate.
 10. Adevice manufacturing method including a lithographic process, wherein inthe lithographic process, a device pattern is transferred onto asubstrate using an exposure apparatus in claim
 1. 11. An exposureapparatus that illuminates a pattern with an energy beam and transfersthe pattern onto a substrate via a projection optical system, theexposure apparatus comprising: a substrate stage on which the substrateis mounted that moves within a two-dimensional plane holding thesubstrate; a supply system that supplies liquid to a space between theprojection optical system and the substrate on the substrate stage; anda recovery system that recovers the liquid, wherein when the substratestage remains stationary relative to the projection optical system, bothliquid supply operation by the supply system and liquid recoveryoperation by the recovery system are stopped while the liquid remains incontact with the projection optical system.
 12. The exposure apparatusof claim 11, wherein the supply system supplies liquid to the spacebetween the projection optical system and the substrate on the substratestage from the front side in a moving direction of the substrate. 13.The exposure apparatus of claim 11, wherein the supply system suppliesliquid to the space between the projection optical system and thesubstrate on the substrate stage from the rear side in a movingdirection of the substrate.
 14. The exposure apparatus of claim 11, theexposure apparatus further comprising: a drive system that drives thesubstrate stage in a predetermined scanning direction with respect tothe energy beam to transfer the pattern onto the substrate in a scanningexposure method.
 15. The exposure apparatus of claim 11, the exposureapparatus further comprising: at least one bubble recovery system thatrecovers bubbles in the liquid at the rear side of the projectionoptical system in a moving direction of the substrate.
 16. The exposureapparatus of claim 11, the exposure apparatus further comprising: aperipheral wall that surrounds at least an optical element closest tothe substrate constituting the projection optical system, and also formsa predetermined clearance with respect to a surface of the substrate onthe substrate stage, wherein the supply system supplies the liquidinside the peripheral wall at a position adjacent to an end section ofthe projection optical system on the substrate side.
 17. A devicemanufacturing method including a lithographic process, wherein in thelithographic process, a device pattern is transferred onto a substrateusing an exposure apparatus in claim
 11. 18. An exposure apparatus thatilluminates a pattern with an energy beam and transfers the pattern ontoa plurality of divided areas on a substrate respectively, via aprojection optical system, the exposure apparatus comprising: asubstrate stage on which the substrate is mounted that moves within atwo-dimensional plane holding the substrate; a peripheral wall thatsurrounds at least an optical element closest to the substrateconstituting the projection optical system, and also forms apredetermined clearance with respect to a surface of the substrate onthe substrate stage; at least one supply system that supplies liquidinside the peripheral wall from a rear side in a moving direction of thesubstrate, the liquid contacting the substrate and the optical elementclosest to the substrate; and a recovery system that recovers the liquidat a front side of the projection optical system in the moving directionof the substrate.
 19. The exposure apparatus of claim 18, wherein thesupply system has a plurality of supply ports in the periphery of anirradiation area on the substrate where the energy beam is irradiatedvia the pattern and the projection optical system during exposure, andswitches the supply port used for supplying the liquid in accordancewith the moving direction of the substrate.
 20. The exposure apparatusof claim 18, the exposure apparatus further comprising: a drive systemthat drives the substrate stage in a predetermined scanning directionwith respect to the energy beam to transfer the pattern onto thesubstrate in a scanning exposure method.
 21. The exposure apparatus ofclaim 20, wherein the supply system has first and second liquid inletsprovided on first and second opposite sides of the irradiation area inthe scanning direction, respectively, and the supply system switchesbetween the first and second inlets that supply the liquid in accordancewith the scanning direction of the substrate.
 22. The exposure apparatusof claim 18, the exposure apparatus further comprising: a plate providedin at least a part of the periphery of a mounted area of the substrateon the substrate stage, the plate having a surface arranged atsubstantially a same height as a surface of the substrate mounted on thesubstrate stage.
 23. The exposure apparatus of claim 18, the exposureapparatus further comprising: at least one bubble recovery system thatrecovers bubbles in the liquid at the rear side of the projectionoptical system in the moving direction of the substrate.
 24. A devicemanufacturing method including a lithographic process, wherein in thelithographic process, a device pattern is transferred onto a substrateusing an exposure apparatus in claim
 18. 25. An exposure apparatus thatilluminates a pattern with an energy beam, moves a substrate in apredetermined scanning direction, and transfers the pattern onto aplurality of divided areas on the substrate via a projection opticalsystem in a scanning exposure method, the exposure apparatus comprising:a substrate stage on which the substrate is mounted that moves within atwo-dimensional plane holding the substrate; a peripheral wall thatsurrounds at least an optical element closest to the substrateconstituting the projection optical system, and also forms apredetermined clearance with respect to a surface of the substrate onthe substrate stage; a supply system that supplies liquid inside theperipheral wall, the liquid contacting the substrate and the opticalelement closest to the substrate; and a recovery system that recovers atleast a part of the liquid from an inside of the peripheral wall. 26.The exposure apparatus of claim 25, wherein a chamber defined inside ofthe peripheral wall and above the liquid has a negative pressure. 27.The exposure apparatus of claim 25, wherein when the substrate stageholding the substrate is moving, the liquid supply by the supply systemand the liquid recovery by the recovery system are performed.
 28. Theexposure apparatus of claim 25, wherein when the substrate stage holdingthe substrate is stationary, liquid supply operation by the supplysystem and liquid recovery operation by the recovery system aresuspended, and a state where the liquid is held within the peripheralwall is maintained.
 29. The exposure apparatus of claim 25, wherein thepredetermined clearance is set to no more than 3 mm.
 30. A devicemanufacturing method including a lithographic process, wherein in thelithographic process, a device pattern is transferred onto a substrateusing an exposure apparatus in claim
 25. 31. An exposure apparatus thattransfers a predetermined pattern on a substrate via a projectionoptical system in a state where a space between the projection opticalsystem and the substrate is filled with liquid, wherein in the casemultiple exposure is performed, a first pattern is transferred onto adivided area on the substrate, and subsequently a second pattern is alsotransferred onto the divided area on the substrate, the liquid beingheld between the projection optical system and the substrate during atime period between the transfer of the first and second patterns.
 32. Adevice manufacturing method including a lithographic process, wherein inthe lithographic process, a device pattern is transferred onto asubstrate using an exposure apparatus in claim
 31. 33. An exposureapparatus that illuminates a pattern with an energy beam and transfersthe pattern onto a substrate via a projection optical system and liquidwhile locally holding the liquid on an image plane side of theprojection optical system, the exposure apparatus comprising: a supplysystem that supplies liquid to the image plane side of the projectionoptical system so as to form an immersion area having a size smallerthan a surface of the substrate that is subjected to exposure; arecovery system that recovers the liquid supplied by the supply system;a substrate stage on which the substrate is mounted that moves within atwo-dimensional plane holding the substrate, wherein the substrate stagehas a flat section which is substantially flush with a surface of thesubstrate held on the substrate stage, and the liquid supplied by thesupply system is held between the projection optical system and the flatsection of the substrate stage during a time period between exposures ofsubstrates.
 34. The exposure apparatus of claim 33, wherein the flatsection is made up of a plurality of members.
 35. The exposure apparatusof claim 33, wherein the substrate stage has a reference member on whichreference marks are formed, and an upper surface of the reference memberis substantially flush with the flat section.
 36. The exposure apparatusof claim 33, wherein the projection optical system and the flat sectionface each other to keep on holding the liquid on the image plane side ofthe projection optical system when exposure operation for the substrateis suspended.
 37. The exposure apparatus of claim 33, wherein: thesubstrate stage is moved to a predetermined position after exposure hasbeen completed for the substrate held on the substrate stage to make theprojection optical system and the flat section face each other, and thenat the position, liquid recovery by the recovery system is performed andafter the liquid has been recovered, the substrate for which exposurehas been completed is unloaded from the substrate stage.
 38. Theexposure apparatus of claim 33, the exposure apparatus furthercomprising: an exhaust system that exhausts gas on an image plane sideof the projection optical system, wherein the supply system beginssupplying the liquid in parallel with exhausting operation of theexhaust system.
 39. The exposure apparatus of claim 33, wherein thesupply system begins supplying the liquid in a state where theprojection optical system and the flat section are facing each other.40. The exposure apparatus of claim 33, the exposure apparatus furthercomprising: a control system that controls movement of the substratestage based on at least one of temperature information of the liquid andpressure information of the liquid.
 41. The exposure apparatus of claim40, wherein the control system controls movement of the substrate stagebased on at least one of temperature information of the liquid andpressure information of the liquid to make an image plane formed by theprojection optical system and a surface of the substrate substantiallycoincide with each other.
 42. A device manufacturing method including alithographic process, wherein in the lithographic process, a devicepattern is transferred onto a substrate using an exposure apparatus inclaim
 33. 43. An exposure apparatus that illuminates a pattern with anenergy beam and transfers the pattern onto a substrate via a projectionoptical system and liquid while locally holding the liquid on an imageplane side of the projection optical system so as to form an immersionarea having a size smaller than a surface of the substrate that issubjected to exposure, the exposure apparatus comprising: a substratestage on which the substrate is mounted that moves within atwo-dimensional plane holding the substrate, wherein the substrate stagehas a flat section substantially flush with a surface of the substrateheld on the substrate stage, and when exposure operation is suspended,the projection optical system and the flat section face each other tokeep on holding the liquid on the image plane side of the projectionoptical system.
 44. The exposure apparatus of claim 43, wherein theliquid is held between the projection optical system and the flatsection when a substrate is loaded onto the substrate stage.
 45. Theexposure apparatus of claim 43, wherein the liquid is held between theprojection optical system and the flat section when a substrate isunloaded from the substrate stage.
 46. A device manufacturing methodincluding a lithographic process, wherein in the lithographic process, adevice pattern is transferred onto a substrate using an exposureapparatus in claim 43.